As filed with the Securities and Exchange Commission on August 26, 2022

Registration No.          

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-4

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

MASTEC, INC.

(Exact name of registrant as specified in its charter)

800 S. Douglas Road, 12th Floor

Coral Gables, Florida 33134

(305) 599-1800

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Alberto de Cardenas

Executive Vice President and Corporate General Counsel

MasTec, Inc.

800 S. Douglas Road, 12th Floor

Coral Gables, Florida 33134

(305) 599-1800

(Name, address, including zip code, and telephone number, including area code, of agent for service)

With copies to:

Approximate date of commencement of proposed sale of the securities to the public: As soon as practicable after this Registration Statement is declared effective and all other conditions to the transaction contemplated by the Agreement and Plan of Merger, dated as of July 24, 2022, described in the enclosed Proxy Statement/Prospectus have been satisfied or waived.

If the securities being registered on this form are being offered in connection with the formation of a holding company and there is compliance with General Instruction G, check the following box.  ☐

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act of 1933, as amended (referred to as the “Securities Act”), check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

If this form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer a smaller reporting company or emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Securities Exchange Act of 1934 (referred to as the “Exchange Act”).

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.  ☐

If applicable, place an X in the box to designate the appropriate rule provision relied upon in conducting this transaction:

Exchange Act Rule 13e-4(i) (Cross-Border Issuer Tender Offer)  ☐

Exchange Act Rule 14d-1(d) (Cross-Border Third-Party Tender Offer)  ☐

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act or until this Registration Statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

The information in this proxy statement/prospectus is subject to completion and amendment. A registration statement relating to the securities described in this proxy statement/prospectus has been filed with the Securities and Exchange Commission. These securities may not be sold nor may offers to buy these securities be accepted prior to the time the registration statement becomes effective. This proxy statement/prospectus shall not constitute an offer to sell or the solicitation of any offer to buy nor shall there be any sale of these securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration under the securities laws of any such jurisdiction.

LETTER TO IEA STOCKHOLDERS

PRELIMINARY—SUBJECT TO COMPLETION, DATED AUGUST 26, 2022

MERGER PROPOSED—YOUR VOTE IS VERY IMPORTANT

Dear Infrastructure and Energy Alternatives, Inc. Stockholder:

On July 24, 2022, Infrastructure and Energy Alternatives, Inc. (referred to as “IEA”), MasTec, Inc. (referred to as “MasTec”) and Indigo Acquisition I Corp., a direct wholly owned subsidiary of MasTec (referred to as “Merger Sub”) entered into an Agreement and Plan of Merger that provides for the acquisition of IEA by MasTec (such agreement, as it may be amended from time to time, the “merger agreement”). Pursuant to the terms of the merger agreement, Merger Sub will merge with and into IEA (referred to as the “merger”), with IEA surviving the merger and becoming a wholly owned subsidiary of MasTec. The respective boards of directors of IEA and MasTec have unanimously approved the merger agreement and the merger.

Upon the terms and subject to the conditions of the merger agreement, at the effective time of the merger, each share of common stock, par value $0.0001 per share, of IEA (referred to as “IEA common stock”) (other than (i) shares held in the treasury of IEA or owned, directly or indirectly, by MasTec, Merger Sub, IEA or any wholly-owned subsidiary of IEA immediately prior to the effective time and (ii) shares held by a holder who did not vote in favor of the adoption of the merger agreement and has properly exercised appraisal rights in respect of such shares in accordance with Section 262 of the General Corporation Law of the State of Delaware) will be automatically converted into the right to receive (i) 0.0483 shares of common stock, par value $0.10 per share, of MasTec (referred to as the “stock consideration”) and (ii) $10.50 per share in cash, without interest (referred to as the “cash consideration”).

Concurrently with the execution of the merger agreement, MasTec entered into voting agreements with each of (i) Ares Special Situations Fund IV, L.P. and ASOF Holdings I, L.P., (ii) John Paul Roehm and Roehm Living Trust and (iii) Derek Glanvill (referred to as the “voting agreements”). Subject to the terms and conditions of the voting agreements, such stockholders have agreed, among other things, to vote all of the shares of IEA common stock held by them (representing in the aggregate approximately 35% of the total outstanding shares of IEA common stock as of July 24, 2022) in favor of the adoption of the merger agreement.

The blended value per share of IEA common stock of $14.00, calculated as of July 24, 2022, represented a premium of approximately 34% over the closing price per IEA common stock of $10.43 on July 22, 2022 and a premium of approximately 57% over the 30-day volume weighted average closing price per IEA common stock ending on July 22, 2022 of $8.94. The implied value of the stock consideration will fluctuate as the market price of MasTec common stock fluctuates because the stock consideration is payable based upon a fixed exchange ratio. As a result, the value of the stock consideration that IEA stockholders will receive upon completion of the merger could be greater than, less than or the same as the value of the stock consideration on the date of the accompanying proxy statement/prospectus, at the time of the special meeting of the IEA stockholders described in the accompanying proxy statement/prospectus (referred to as the “special meeting”) or at the closing of the merger. Accordingly, you should obtain current stock price quotations for MasTec common stock and IEA common stock before deciding how to vote with respect to the approval of the merger agreement proposal. MasTec common stock and IEA common stock trade on the New York Stock Exchange and The Nasdaq Global Select Market under the symbols “MTZ” and “IEA,” respectively.

Based on the number of shares of MasTec common stock and IEA common stock outstanding on [●], 2022, upon completion of the merger, former IEA stockholders will own approximately [●]% of the outstanding shares of MasTec common stock.

The IEA board of directors unanimously (i) determined that the terms of the merger agreement and the transactions contemplated thereby, including the merger, are fair to, and in the best interests of, IEA and its stockholders, (ii) determined that it is in the best interests of IEA and its stockholders, and declared it advisable to, enter into the merger agreement, (iii) approved the execution and delivery by IEA of the merger agreement, the performance by IEA of its covenants and agreements contained therein and the consummation of the merger and the other transactions contemplated by the merger agreement upon the terms and subject to the conditions set forth in the merger agreement and (iv) resolved to recommend that the IEA stockholders vote to adopt the merger agreement.

At the special meeting, you will be asked to approve the merger agreement proposal and to vote on other transaction-related matters. The IEA board of directors unanimously recommends that IEA stockholders vote “FOR” the merger agreement proposal and “FOR” each of the other proposals described in the accompanying proxy statement/prospectus.

Your vote is very important. MasTec and IEA cannot complete the merger without the approval of the merger agreement proposal by IEA stockholders holding at least a majority of the shares of IEA common stock outstanding at the close of business on [●], 2022, the record date for the special meeting. The failure of any stockholder to vote will have the same effect as a vote against the approval of the merger agreement proposal. It is important that your shares of IEA common stock be represented and voted regardless of the size of your holdings. Whether or not you plan to participate in the special meeting, IEA urges you to submit a proxy in advance of the special meeting to have your shares voted by using one of the methods described in the accompanying proxy statement/prospectus.

More information about MasTec, IEA, the special meeting, the transactions and the other proposals for consideration at the special meeting is contained in the accompanying proxy statement/prospectus. Please carefully read the entire proxy statement/prospectus, including the section titled “Risk Factors” beginning on page 24, for a discussion of the risks relating to the merger, and the annexes and documents incorporated by reference. You may also obtain more information about IEA from the documents IEA files with the U.S. Securities and Exchange Commission, including those incorporated by reference into the accompanying proxy statement/prospectus.

On behalf of the IEA board of directors, thank you for your continued support.

Sincerely,

Erin Roth

Executive Vice President, General Counsel and Corporate Secretary

NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES COMMISSION HAS APPROVED OR DISAPPROVED THE MERGER OR OTHER TRANSACTIONS DESCRIBED IN THE ACCOMPANYING PROXY STATEMENT/PROSPECTUS OR THE SECURITIES TO BE ISSUED PURSUANT TO THE MERGER UNDER THE ACCOMPANYING PROXY STATEMENT/PROSPECTUS NOR HAVE THEY DETERMINED IF THE ACCOMPANYING PROXY STATEMENT/PROSPECTUS IS ACCURATE OR ADEQUATE. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.

The accompanying proxy statement/prospectus is dated [●], 2022 and is first being mailed to IEA stockholders on or about [●], 2022.

NOTICE OF SPECIAL MEETING OF IEA’S STOCKHOLDERS

PRELIMINARY—SUBJECT TO COMPLETION, DATED AUGUST 26, 2022

INFRASTRUCTURE AND ENERGY ALTERNATIVES, INC.

6325 Digital Way, Suite 460

Indianapolis, Indiana 46278

NOTICE OF SPECIAL MEETING OF STOCKHOLDERS TO BE HELD ON [●], 2022

This is a notice that the special meeting of stockholders of Infrastructure and Energy Alternatives, Inc. (referred to as “IEA”) will be held on [●], 2022, beginning at [●]. The special meeting will be a completely virtual, live audio webcast meeting of stockholders and will be held for the following purposes:

The accompanying proxy statement/prospectus describes the proposals listed above in more detail. Please refer to the accompanying proxy statement/prospectus, including the merger agreement and the other annexes and documents included in, or incorporated by reference into, the accompanying proxy statement/prospectus for further information with respect to the business to be transacted at the special meeting. You are encouraged to read the entire proxy statement/prospectus carefully before voting. In particular, see the section titled “Risk Factors” beginning on page 24.

The IEA board of directors unanimously (i) determined that the terms of the merger agreement and the transactions contemplated thereby, including the merger, are fair to, and in the best interests of, IEA and its stockholders, (ii) determined that it is in the best interests of IEA and its stockholders, and declared it advisable, to enter into the merger agreement, (iii) approved the execution and delivery by IEA of the merger agreement, the performance by IEA of its covenants and agreements contained therein and the consummation of the merger and the other transactions contemplated by the merger agreement upon the terms and subject to the conditions set forth in the merger agreement and (iv) resolved to recommend that the IEA stockholders vote to adopt the merger agreement. The IEA board of directors unanimously recommends that IEA stockholders vote “FOR” the merger agreement proposal and “FOR” each of the other proposals listed above and described in more detail in the accompanying proxy statement/prospectus.

The IEA board of directors has fixed the close of business on [●], 2022 as the record date for determination of IEA stockholders entitled to receive notice of, and to vote at, the special meeting or any adjournments or postponements thereof. Only holders of record of IEA common stock as of the close of business on the record date are entitled to receive notice of, and to vote at, the special meeting.

YOUR VOTE IS VERY IMPORTANT, REGARDLESS OF THE NUMBER OF SHARES THAT YOU OWN.

The merger cannot be completed unless the merger agreement proposal is approved by the affirmative vote, virtually or by proxy, of holders of at least a majority of the outstanding shares of IEA common stock entitled to vote thereon. The failure to vote will have the same effect as a vote against the merger agreement proposal. The affirmative vote of a majority of the votes cast by the stockholders present in person or represented at the special meeting, virtually or by proxy, and entitled to vote on the merger-related compensation proposal and the adjournment proposal, is required to approve such proposals.

For more information concerning the special meeting, the merger agreement, the merger and the other transactions contemplated by the merger agreement, please review the accompanying proxy statement/prospectus and the copy of the merger agreement attached as Annex A to the proxy statement.

Whether or not you expect to participate in the special meeting, IEA urges you to submit a proxy to have your shares voted as promptly as possible either: (1) via the Internet at proxyvote.com (see proxy card for instructions); (2) by telephone (see proxy card for instructions); or (3) by completing, signing and returning the enclosed proxy card in the postage-paid envelope provided, so that your shares may be represented and voted at the special meeting. If your shares are held in “street name” by a bank, brokerage firm or other nominee, please follow the instructions on the voting instruction card furnished by such bank, brokerage firm or other nominee. Any stockholder of record participating in the special meeting may vote even if such stockholder has returned a proxy card. However, if your shares are held in “street name” you must obtain a legal proxy from the bank, brokerage firm or nominee to vote at the special meeting.

Stockholders of record as of [●], 2022 will be able to participate in the special meeting by visiting [●] and entering the [●]-digit control number included on your proxy card or voting instruction card that accompanied your proxy materials.

A stockholder who does not vote in favor of the merger agreement proposal will have the right to seek appraisal of the fair value of its shares if the merger is consummated, but only if such stockholder submits a written demand for appraisal to IEA prior to the time the vote is taken on the merger agreement proposal and complies with all other requirements of the Delaware General Corporation Law (referred to as the “DGCL”). A copy of the applicable DGCL statutory provisions is included as Annex F to the accompanying proxy statement, and a summary of these provisions can be found under the section entitled “Appraisal Rights” in the accompanying proxy statement.

If you have any questions about the special meeting, the merger, the proposals or the accompanying proxy statement/prospectus, would like additional copies of the proxy statement/prospectus, need to obtain proxy cards or other information related to this proxy solicitation or need help submitting a proxy or voting your shares of IEA common stock, you should contact:

Infrastructure and Energy Alternatives, Inc.

6325 Digital Way, Suite 460

Indianapolis, Indiana 46278

(800) 688-3775

Attention: Investor Relations

or

D.F. King & Co., Inc.

48 Wall Street, 22nd Floor

New York, New York 10005

Banks and Brokers may call: (212) 269-5550

Stockholders may call toll free: (866) 796-3441

IEA@dfking.com

By order of the board of directors

Erin Roth

Executive Vice President, General Counsel and Corporate Secretary

Dated: [●], 2022

Indianapolis, Indiana

REFERENCES TO ADDITIONAL INFORMATION

MasTec, Inc. (referred to as “MasTec”) has filed a registration statement on Form S-4 to which this proxy statement/prospectus relates. This proxy statement/prospectus does not contain all of the information included in the registration statement or in the exhibits to the registration statement to which the accompanying proxy statement/prospectus relates.

This proxy statement/prospectus also incorporates by reference important business and financial information about MasTec and Infrastructure and Energy Alternatives, Inc. (referred to as “IEA”) from documents previously filed by MasTec or IEA with the U.S. Securities and Exchange Commission (referred to as the “SEC”), that are not included in or delivered with this proxy statement/prospectus. In addition, MasTec and IEA each file annual, quarterly and current reports, proxy statements and other business and financial information with the SEC.

This proxy statement/prospectus and the Annexes hereto, the registration statement to which this proxy statement/prospectus relates and the exhibits thereto, the information incorporated by reference herein and the other information filed by MasTec and IEA with the SEC is available for you to review at the SEC’s Public Reference Room located at 100 F Street, N.E., Room 1580, Washington, DC 20549. You can also obtain these documents through the SEC’s website at www.sec.gov or on either MasTec’s website at https://investors.mastec.com/financial-reporting/sec-filings in the “Investors” section or on IEA’s website at https://ir.iea.net/sec-filings in the “Investors” section. By referring to MasTec’s website, IEA’s website, and the SEC’s website, MasTec and IEA do not incorporate any such website or its contents into this proxy statement/prospectus.

This proxy statement/prospectus incorporates important business and financial information about MasTec and IEA from other documents that are not included in or delivered with this proxy statement/prospectus. This information is available to you without charge upon your request. You can obtain these documents incorporated by reference into this proxy statement/prospectus by requesting them in writing or by telephone from the appropriate company at the following addresses and telephone numbers:

See “Incorporation of Certain Documents by Reference” beginning on page 113 for more information about the documents incorporated by reference in this proxy statement/prospectus.

If you hold your shares in “street name,” through a bank, broker or other nominee, you should contact such bank, broker or other nominee if you need to obtain a voting instruction card or have questions on how to vote your shares.

ABOUT THIS PROXY STATEMENT/PROSPECTUS

This proxy statement/prospectus, which forms part of a registration statement on Form S-4 filed with the SEC by MasTec (Registration No. 333-[●]), constitutes a prospectus of MasTec under Section 5 of the Securities Act of 1933, as amended (referred to as the “Securities Act”), with respect to the shares of common stock of MasTec, par value $0.10 per share, to be issued pursuant to the merger agreement. This document also constitutes a notice of meeting and a proxy statement under Section 14(a) of the Securities Exchange Act of 1934, as amended (referred to as the “Exchange Act”), with respect to the IEA special meeting, at which IEA stockholders will be asked to consider and vote on, among other matters, a proposal to adopt the merger agreement.

No one has been authorized to provide you with information that is different from that contained in, or incorporated by reference into, this proxy statement/prospectus. This proxy statement/prospectus is dated [●]. The information contained in this proxy statement/prospectus is accurate only as of that date or, in the case of information in a document incorporated by reference, as of the date of such document, unless the information specifically indicates that another date applies.

This proxy statement/prospectus does not constitute an offer to sell, or a solicitation of an offer to buy, any securities, or the solicitation of a proxy, in any jurisdiction in which or from any person to whom it is unlawful to make any such offer or solicitation in such jurisdiction.

The information concerning MasTec contained in this proxy statement/prospectus or incorporated by reference has been provided by MasTec, and the information concerning IEA contained in this proxy statement/prospectus has been provided by IEA.

TABLE OF CONTENTS

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QUESTIONS AND ANSWERS ABOUT THE TRANSACTION AND THE SPECIAL MEETING

The following are brief answers to common questions that you may have regarding the merger agreement, the transaction, the consideration to be received in the transaction and the special meeting (as discussed below). The questions and answers in this section may not address all questions that might be important to you as an IEA stockholder. To better understand these matters, and for a description of the legal terms governing the transaction, we urge you to read carefully and in its entirety this proxy statement/prospectus, including the Annexes to, and the documents incorporated by reference in, this proxy statement/prospectus, as well as the registration statement to which this proxy statement/prospectus relates, including the exhibits to the registration statement. See “Incorporation of Certain Documents by Reference” beginning on page 113 and “Where You Can Find More Information” beginning on page 115.

No fractional shares of MasTec common stock will be issued in the merger. IEA stockholders will receive cash, without interest, in lieu of any fractional shares.

Your vote is very important. We encourage you to submit a proxy or voting instructions as soon as possible.

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For more information concerning options and other equity compensation, see “The Agreements – Transaction Structure – Treatment of Stock Options, Warrants and Other Equity-Based Awards.”

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For more information concerning options and other equity compensation, see “The Agreements – Transaction Structure – Treatment of Stock Options, Warrants and Other Equity-Based Awards.”

An IEA stockholder that is a Non-U.S. Holder (as defined in the section entitled “Transaction Summary – Material U.S. Federal Income Tax Consequences of the Merger – Non-U.S. Holders”) generally will not be subject to U.S. federal income tax with respect to the exchange of shares of IEA common stock for cash and shares of MasTec common stock in the merger unless such Non-U.S. Holder has certain connections to the

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United States as described in “Transaction Summary – Material U.S. Federal Income Tax Consequences of the Merger – Non-U.S. Holders”

Please carefully review the information set forth in the section “Transaction Summary – Material U.S. Federal Income Tax Consequences of the Merger” beginning on page 70 for a description of the material U.S. federal income tax consequences of the merger. The tax consequences of the merger will depend on your own situation. Please consult your own tax advisors as to the specific tax consequences of the merger to you.

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As of [●], 2022, the record date, IEA directors and executive officers, as a group, owned and were entitled to vote [●] shares of IEA common stock, or approximately [●]% of the outstanding shares of IEA common stock. IEA currently expects that these directors and executive officers will vote their shares in favor of the merger agreement proposal and each of the other proposals described in this proxy statement/prospectus, although none of them are obligated to do so, other than John Paul Roehm and Derek Glanvill.

Concurrently with the execution of the merger agreement, each of (i) Derek Glanvill (the current chairman and a member of the IEA board of directors), (ii) John Paul Roehm (the current Chief Executive Officer and a member of the IEA board of directors) and Roehm Living Trust (collectively referred to as the “Roehm stockholders”) and (iii) Ares Special Situations Fund IV, L.P. and ASOF Holdings I, L.P. (the foregoing entities listed in this clause (iii), collectively referred to as the “Ares stockholders”) entered into agreements with MasTec (referred to as the “voting agreements”) pursuant to which each such party agreed, among other things and subject to the terms and conditions of the voting agreements, to vote the shares of IEA common stock held by such party in favor of the merger agreement proposal. See the section titled “The Agreements – Description of the Voting Agreements.”

As of [●], 2022, the record date, an aggregate of [●] shares of IEA common stock, or approximately [●]% of the outstanding shares of IEA common stock, were subject to the voting agreements, which are attached to this proxy statement/prospectus as Annex B, Annex C and Annex D.

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If you are a beneficial owner, please refer to the instructions provided by your bank, brokerage firm or other nominee as to how to vote your shares.

Additional information on participating in the special meeting can be found under the section titled “Information About the IEA Special Meeting and Proposals.”

Under applicable stock exchange rules, your bank, brokerage firm or other nominee cannot vote your shares of IEA common stock on “non-routine” matters without your instructions. If you do not provide these instructions, a “non-vote” occurs with respect to those matters. The merger agreement proposal, the merger-related compensation proposal and the adjournment proposal will be considered “non-routine” matters. Accordingly, if you do not provide your bank, brokerage firm or other nominee instructions on how to vote your shares of IEA common stock at the special meeting, your bank, brokerage firm or other nominee generally will not be permitted to vote your shares on any of the proposals at the special meeting. IEA strongly encourages you to provide voting instructions to your bank, brokerage firm or other nominee so that your vote will be counted on all matters.

If your shares are held by a bank, brokerage firm or other nominee, you are considered the beneficial owner of shares held in “street name,” and, for the purposes of this proxy statement/prospectus, a beneficial owner,

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and your bank, brokerage firm or other nominee is considered the stockholder of record with respect to those shares. If you are a beneficial owner, you have a right to direct your bank, brokerage firm or other nominee on how to vote the shares held in your account. The availability of Internet or telephonic voting will depend on the nominee’s voting process. Please check with your bank, brokerage firm or other nominee and follow the voting procedures your bank, brokerage firm or other nominee provides.

Participation in the virtual special meeting will not, however, in and of itself, constitute a vote or revocation of a prior proxy.

Beneficial owners of shares held in “street name” may change their voting instructions only by following the directions received from their bank, brokerage firm or other nominee for changing their voting instructions.

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Infrastructure and Energy Alternatives, Inc.

6325 Digital Way, Suite 460,

Indianapolis, Indiana 46278

(765)-828-2707

Attention: Investor Relations

or

D.F. King & Co., Inc.

48 Wall Street, 22nd Floor

New York, New York 10005

Banks and Brokers may call: (212) 269-5550

Stockholders may call toll free: (866) 796-3441

IEA@dfking.com

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RISK FACTORS

In addition to the other information included in, incorporated by reference in, or found in the Annexes attached to, this proxy statement/prospectus, including the matters addressed in “Cautionary Note Regarding Forward-Looking Statements” beginning on page 28, you should carefully consider the following risk factors in deciding whether to vote for the proposals to be considered at the special meeting. See “Where You Can Find More Information” beginning on page 115 and “Incorporation of Certain Documents by Reference” beginning on page 113 for more information about the documents incorporated by reference in this proxy statement/prospectus. Additional risks and uncertainties not presently known to MasTec or IEA or that are not currently believed to be important also may adversely affect the transaction and MasTec following the transaction.

Risks Relating to the Merger

Because the stock exchange ratio is fixed and will not be adjusted for stock price changes and the market price of MasTec common stock has fluctuated and will continue to fluctuate, IEA stockholders cannot be sure of the value of the consideration they will receive.

Upon completion of the merger, each issued and outstanding share of IEA common stock (other than (i) cancelled shares and (ii) dissenting shares) will be converted into the right to receive $10.50 in cash, without interest, and 0.0483 of a share of MasTec common stock.

The market price of MasTec common stock at the time of completion of the merger may vary significantly from the market price of MasTec common stock on the date the merger agreement was executed, the date of this proxy statement/prospectus and the date of the IEA special meeting. Because the stock consideration is payable in a fixed exchange ratio, the value of the stock consideration that IEA stockholders receive upon completion of the merger may be higher or lower than the value of the stock consideration on such earlier dates. Accordingly, IEA stockholders will not know or be able to calculate at the time of the IEA special meeting the market value of the stock consideration they will receive upon completion of the merger.

If the market value of MasTec common stock falls between the date of this proxy statement/prospectus and the time the merger consideration is actually received, the value of the merger consideration received may be less than the value of the merger consideration such stockholder may anticipate receiving.

Stock price changes may result from a variety of factors, including, among others, general market and economic conditions, changes in MasTec’s and IEA’s respective businesses, operations and prospects, market assessments of the likelihood that the merger will be completed, the timing of the merger, regulatory considerations and other risk factors set forth or incorporated by reference in this proxy statement/prospectus. Many of these factors are beyond MasTec’s and IEA’s control.

Completion of the merger is subject to the conditions contained in the merger agreement and if these conditions are not satisfied or waived, the merger will not be completed.

The obligations of MasTec and IEA to complete the merger are subject to the satisfaction or waiver of a number of conditions, including, among others, the adoption of the merger agreement by IEA’s stockholders by the affirmative vote of at least a majority of the outstanding shares of IEA common stock and the expiration or termination of the waiting period under the HSR Act. For a more complete summary of the required regulatory approvals and the closing conditions, see the section titled “Summary – Regulatory Approvals Required for the Merger.”

Although MasTec and IEA have agreed in the merger agreement to use their reasonable best efforts to complete the merger as promptly as practicable, many of the closing conditions are not within MasTec’s or IEA’s control, and neither company can predict when or if these conditions will be satisfied. If any of these conditions are not satisfied or waived prior to July 24, 2023, which deadline may be extended to October 24, 2023 under

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certain circumstances, it is possible that the merger agreement will be terminated. The failure to satisfy all of the required conditions could delay the completion of the merger for a significant period of time or prevent it from occurring. There can be no assurance that the closing conditions will be satisfied or waived or that the merger will be completed. See the risk factor titled “—Failure to complete the merger could negatively affect the stock price and the future business and financial results of IEA,” below.

Regulatory approval may not be received, may take longer than expected or may impose conditions that are not presently anticipated or cannot be met.

Before the merger may be completed, any applicable waiting period (and any extension thereof) under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, and the rules and regulations thereunder relating to the transactions contemplated by the merger agreement, must have expired or been terminated. Under the merger agreement, MasTec and IEA have agreed to use their reasonable best efforts to obtain regulatory approvals, consents and clearances and therefore may be required to comply with conditions, terms, obligations or restrictions imposed by governmental authorities. There can be no assurance that such conditions, terms, obligations or restrictions will not have the effect of delaying completion of the merger or imposing additional material costs on or materially limiting the revenues of MasTec following the completion of the merger. In addition, neither MasTec nor IEA can provide assurance that any such conditions, terms, obligations or restrictions will not result in the delay or abandonment of the merger. See the section titled “Summary – Regulatory Approvals Required for the Merger.”

IEA’s directors and executive officers have interests in the merger that may be different from, or in addition to, your interests as a stockholder of IEA more generally.

When considering the recommendation of the IEA board of directors that IEA stockholders approve the merger agreement proposal and the merger-related compensation proposal, IEA stockholders should be aware that directors and executive officers of IEA have certain interests in the merger that may be different from, or in addition to, the interests of IEA stockholders more generally. These interests generally include, among others, treatment of outstanding IEA equity awards in connection with the merger and certain potential severance payments in connection with the merger and a qualifying termination of employment upon or following the merger. See the section titled “Transaction Summary – Interests of IEA’s Directors and Executive Officers in the Transaction” for a more detailed description of these interests. The IEA board of directors was aware of these interests and considered them, among other matters, in evaluating and negotiating the merger agreement, in reaching its decision to approve the merger agreement and the consummation of the merger, and in recommending that IEA stockholders vote in favor of the merger agreement proposal.

The merger agreement limits IEA’s ability to pursue alternatives to the merger and may discourage other companies from trying to acquire IEA.

The merger agreement contains provisions that make it more difficult for IEA to sell its business to a party other than MasTec. These provisions include a general prohibition on IEA soliciting any company takeover proposal or offer for a competing transaction. In addition, upon termination of the merger agreement, IEA is required to pay MasTec a termination fee of $27.5 million if the merger agreement is terminated in certain circumstances including IEA entering into a definitive agreement with respect to a superior proposal or an adverse recommendation change.

The merger agreement subjects IEA to restrictions on its business activities.

The merger agreement subjects IEA to restrictions on its business activities and obligates IEA to generally conduct its business in a commercially reasonable manner and in all material respects in the ordinary course of business consistent with past practice. These restrictions could have an adverse effect on IEA’s results of operations, cash flows and financial position.

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The business relationships of MasTec and IEA and their respective subsidiaries may be subject to disruption due to uncertainty associated with the merger, which could have an adverse effect on the results of operations, cash flows and financial position of MasTec, IEA and, following the completion of the merger, MasTec.

Parties with which MasTec and IEA, or their respective subsidiaries, do business may be uncertain as to the effects the merger may have on them, including with respect to current or future business relationships with MasTec, IEA or their respective subsidiaries. These relationships may be subject to disruption as customers, suppliers and other persons with whom MasTec and IEA have a business relationship may delay or defer certain business decisions or might decide to terminate, change or renegotiate their relationships with MasTec or IEA, as applicable, or consider entering into business relationships with parties other than MasTec, IEA or their respective subsidiaries. These disruptions could have an adverse effect on the results of operations, cash flows and financial position of MasTec or IEA, including an adverse effect on MasTec’s ability to realize the expected synergies and other benefits of the merger. The risk, and adverse effect, of any disruption could be exacerbated by a delay in completion of the merger or termination of the merger agreement.

Failure to complete the merger could negatively affect the stock price and the future business and financial results of IEA.

If the merger is not completed for any reason, including as a result of IEA stockholders failing to approve the merger agreement proposal, the ongoing business of IEA may be adversely affected and, without realizing any of the benefits of having completed the merger, IEA could be subject to a number of negative consequences, including the following:

In addition, upon termination of the merger agreement, under certain circumstances, IEA is required to pay MasTec a termination fee of $27.5 million, including IEA entering into a definitive agreement with respect to a superior proposal or an adverse recommendation change. Finally, IEA could be subject to litigation related to any failure to complete the merger or related to any enforcement proceeding commenced against IEA to perform its obligations under the merger agreement. If the merger is not completed, any of these risks may materialize and may adversely affect IEA’s businesses, financial condition, financial results and stock price.

MasTec expects to obtain financing in connection with the merger and cannot guarantee that it will be able to obtain such financing on favorable terms or at all.

MasTec anticipates that the funds needed to complete the merger will be derived from a combination of (i) available cash on hand and (ii) third-party debt financing. See “Transaction Summary - Financing of the

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Transaction” for additional information regarding the anticipated financing of the merger. MasTec’s ability to obtain any such new debt financing will depend on, among other factors, prevailing market conditions and other factors beyond MasTec’s control. MasTec cannot assure you that it will be able to obtain new debt financing on terms acceptable to it or at all, and any such failure could materially adversely affect its operations and financial condition. MasTec’s obligation to complete the merger is not conditioned upon the receipt of any financing.

Lawsuits may in the future be filed against IEA, its directors, MasTec and/or Merger Sub challenging the merger, and an adverse ruling in any such lawsuit may prevent completing the merger or completing the merger within the expected timeframe and/or result in substantial costs to MasTec and IEA.

Securities class action lawsuits and derivative lawsuits are often brought against public companies that have entered into acquisition, merger or other business combination agreements like the merger agreement. Even if such a lawsuit is without merit, defending against these claims can result in substantial costs and divert management time and resources. An adverse judgment could result in monetary damages, which could have a negative impact on MasTec’s and IEA’s respective liquidity and financial condition.

Further, one of the conditions to the completion of the merger is that no injunction or law by any governmental entity of competent jurisdiction will be in effect that has the effect of restraining, enjoining or otherwise prohibiting the consummation of the merger. As such, if an injunction prohibiting the consummation of the merger is obtained, that injunction may prevent the merger from becoming effective or from becoming effective within the expected timeframe.

Risk Factors Relating to MasTec after the Transaction

Following the completion of the transaction, MasTec will continue to be subject to the risks described in Part I, Item 1A in MasTec’s Annual Report on Form 10-K for the fiscal year ended December 31, 2021, as updated by MasTec’s Quarterly Reports on Form 10-Q and other filings with the SEC. See the section entitled “Where You Can Find More Information” beginning on page 115 of this proxy statement/prospectus.

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CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This proxy statement/prospectus and the documents that are incorporated into this proxy statement/prospectus by reference may contain or incorporate by reference statements that do not directly or exclusively relate to historical facts. Such statements are “forward-looking statements.” You can typically identify forward-looking statements by the use of forward-looking words, such as “may,” “will,” “should,” “could,” “would,” “predicts,” “future,” “project,” “believe,” “anticipate,” “expect,” “estimate,” “continue,” “potential,” “plan,” “aim,” “seek,” “forecast” and other similar words. These include, but are not limited to, statements relating to the strategy of MasTec after the closing of the transaction, the synergies and the benefits that are expected to be achieved as a result of the merger, including future financial and operating results, MasTec’s plans after the closing of the transaction, objectives, expectations and intentions, MasTec’s and IEA’s projections and other prospective financial information, as well as other statements that are not historical facts. These forward-looking statements represent our intentions, plans, expectations, assumptions and beliefs about future events including the operations of MasTec after the closing of the transaction and are subject to risks, uncertainties and other factors. Many of those factors are outside the control of MasTec and IEA, and could cause actual results to differ materially from the results expressed or implied by those forward-looking statements. In addition to the risk factors described under “Risk Factors” beginning on page 24, those factors include:

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The areas of risk and uncertainty described above should be considered in connection with any written or oral forward-looking statements that may be made after the date of this proxy statement/prospectus by MasTec or IEA or anyone acting for any or all of them. Except for their ongoing obligations to disclose material information under the U.S. federal securities laws, neither MasTec nor IEA undertakes any obligation to release publicly any revisions to any forward-looking statements, to report events or circumstances after the date of this proxy statement/prospectus or to report the occurrence of unanticipated events.

For additional information about factors that could cause actual results to differ materially from those described in the forward-looking statements, see the note regarding forward-looking statements in MasTec’s Annual Report on Form 10-K for the year ended December 31, 2021, as filed with the SEC and incorporated by reference in this proxy statement/prospectus, and the special note regarding forward-looking statements in IEA’s Annual Report on Form 10-K for the year ended December 31, 2021, as filed with the SEC and incorporated by reference in this proxy statement/prospectus. See “Incorporation of Certain Documents by Reference” beginning on page 113 and “Where You Can Find More Information” on page 115.

MasTec and IEA also caution the reader that undue reliance should not be placed on any forward-looking statements, which speak only as of the date of this proxy statement/prospectus. Neither MasTec nor IEA undertakes any duty or responsibility to update any of these forward-looking statements to reflect events or circumstances after the date of this proxy statement/prospectus or to reflect actual outcomes.

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INFORMATION ABOUT THE IEA SPECIAL MEETING AND PROPOSALS

General

This proxy statement/prospectus is first being mailed on or about [●], 2022 and constitutes notice of the special meeting in conformity with the requirements of the DGCL and the IEA bylaws.

This proxy statement/prospectus is being provided to IEA stockholders as part of a solicitation of proxies by the IEA board of directors for use at the special meeting of IEA stockholders and at any adjournments or postponements of such special meeting. This proxy statement/prospectus provides IEA stockholders with information about the special meeting and should be read carefully in its entirety.

Date, Time and Place of the Special Meeting

The special meeting will be held on [●], 2022, beginning at [●], unless postponed to a later date, via live audio webcast at [●]. To virtually participate in the special meeting, visit [●] and enter the [●]-digit control number provided on your proxy card or voting instruction card in order to participate in the special meeting.

Purposes of the Special Meeting

At the special meeting, IEA stockholders will be asked to vote upon the following proposals:

Only the approval of the merger agreement proposal is required for completion of the merger. IEA will transact no other business at the special meeting except such business as may properly be brought before the special meeting or any adjournment or postponement thereof.

Record Date

The record date for the determination of stockholders entitled to notice of and to vote at the special meeting is [●], 2022 (referred to as the “record date”).

Virtual Participation at Special Meeting

The special meeting will be a completely virtual meeting of stockholders conducted via live audio webcast through the website described above under the heading “Date, Time and Place of the Special Meeting.” Only IEA stockholders who held shares of record as of the close of business on the record date are entitled to receive notice of and vote at the special meeting and any adjournment or postponement of the special meeting, as long as such shares remain outstanding on the date of the special meeting. IEA’s official stock ownership records will conclusively determine whether a stockholder is a “holder of record” as of the record date.

IEA will have technicians ready to assist IEA stockholders with any technical difficulties they may have accessing the virtual meeting. If IEA stockholders encounter any difficulties accessing the virtual meeting or during the meeting time, IEA stockholders should navigate to [●], where a phone number for IT support will be posted.

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Outstanding Shares as of Record Date

As of the record date, there were [●] shares of IEA common stock outstanding and owned by stockholders (i.e., excluding shares of IEA common stock held in treasury by IEA), held by [●] holders of record. Each share of IEA common stock is entitled to one vote on each matter considered at the special meeting.

Stockholders may request an appointment to inspect a complete list of stockholders entitled to vote at the special meeting for any purpose germane to the special meeting at IEA’s headquarters, located at 6325 Digital Way, Suite 460, Indianapolis, Indiana 46278, during ordinary business hours within ten days prior to the special meeting by sending an email request to investors@iea.net.

Shares and Voting of IEA’s Directors and Executive Officers

As of the record date, IEA directors and executive officers, as a group, owned and were entitled to vote [●] shares of IEA common stock, or approximately [●]% of the outstanding shares of IEA common stock. IEA currently expects that these directors and executive officers will vote their shares in favor of the merger agreement proposal and each of the other proposals described in this proxy statement/prospectus, although none of the directors and executive officers are obligated to do so, other than John Paul Roehm and Derek Glanvill.

Derek Glanvill is the current chairman and a member of the IEA board of directors. John Paul Roehm, a member of the IEA board of directors, is IEA’s Chief Executive Officer. Further, each of Matt Underwood and Scott Graves are members of the IEA board of directors and are Partners at Ares Management LLC (“Ares Management”), which manages the Ares stockholders. As noted above, pursuant to the voting agreements, each of Derek Glanvill, the Roehm stockholders and the Ares stockholders have agreed to vote all of the shares of IEA common stock held by them (representing in the aggregate approximately [●]% of the total outstanding shares of IEA common stock as of the record date) in favor of the merger agreement proposal. See the section titled “The Voting Agreements.”

Quorum and Broker Non-Votes

In order to conduct any business at the special meeting, a quorum must be present virtually or represented by proxy. Holders of shares representing at least a majority of the voting power of all outstanding shares of capital stock of IEA entitled to vote at the special meeting, represented virtually or by proxy, constitutes a quorum. Stockholders choosing to abstain from voting will be treated as present for purposes of determining whether a quorum is present, but will not be counted as votes cast “FOR” any matter.

Banks, brokerage firms and other nominees who hold shares in “street name” for the accounts of their clients may vote such shares either as directed by their clients or in their own discretion on “routine” matters. When a broker does not receive instructions from a beneficial owner on how to vote shares with respect to a “non-routine” matter, a broker “non-vote” occurs. Broker “non-votes” will be treated as present for purposes of determining whether a quorum is present, but will not be counted as votes cast “FOR” any matter.

Your shares will be counted for purposes of determining if there is a quorum, whether representing votes for, against or abstained, if you (1) participate in the special meeting, or (2) have voted via the Internet, by telephone or by properly submitting a proxy card or voting instruction card by mail.

Required Vote

The votes required for each proposal are as follows:

The Merger Agreement Proposal. The affirmative vote, virtually or by proxy, of holders of at least a majority of the outstanding shares of IEA common stock entitled to vote on the merger agreement proposal is required to approve the merger agreement proposal. Failures to vote, abstentions and broker non-votes will have the same effect as a vote “AGAINST” the merger agreement proposal.

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The Merger-Related Compensation Proposal. The affirmative vote of a majority of the votes cast by the stockholders present in person or represented at the special meeting, virtually or by proxy, and entitled to vote on the merger-related compensation proposal, is required to approve, on an advisory (non-binding) basis, the merger-related compensation proposal. If you are an IEA stockholder on the record date and (i) participate in the special meeting but fail to vote or (ii) mark your proxy card or voting instruction card to abstain, it will have no effect on the merger-related compensation proposal (assuming a quorum is present). If you do not participate in the special meeting, virtually or by proxy, and do not instruct your bank, brokerage firm or other nominee how to vote your shares, it will have no effect on the merger-related compensation proposal (assuming a quorum is present).

The Adjournment Proposal. The affirmative vote of a majority of the votes cast by the stockholders present in person or represented at the special meeting, virtually or by proxy, and entitled to vote on the adjournment proposal, is required to approve the adjounrment proposal. If you are an IEA stockholder on the record date and (i) participate in the special meeting but fail to vote or (ii) mark your proxy card or voting instruction card to abstain, it will have no effect on the adjournment proposal. If you do not participate in the special meeting, virtually or by proxy, and do not instruct your bank, brokerage firm or other nominee how to vote your shares, it will have no effect on the adjournment proposal.

As noted above, pursuant to the voting agreements, each of Derek Glanvill, the Roehm stockholders and the Ares stockholders have agreed to vote all of the shares of IEA common stock held by them (representing in the aggregate approximately [●]% of the total outstanding shares of IEA common stock as of the record date) in favor of the merger agreement proposal. See the section titled “The Agreements – Description of the Voting Agreements.”

How to Vote or Have Your Shares Voted

IEA stockholders of record may vote their shares of IEA common stock or submit a proxy to have their shares of IEA common stock voted at the special meeting in one of the following ways:

Whether or not you plan to participate in the special meeting, IEA urges you to submit your proxy by completing and returning the proxy card as promptly as possible, or by submitting your proxy by telephone or via the Internet, prior to the special meeting to ensure that your shares of IEA common stock will be represented and voted at the special meeting if you are unable to participate.

The IEA board of directors has appointed certain persons as proxy holders to vote proxies in accordance with the instructions of IEA stockholders. If you are a stockholder of record and you authorize these proxy holders to vote your shares of IEA common stock with respect to any matter to be acted upon, your shares will be voted in accordance with your instructions in your proxy. If you are a stockholder of record and you authorize

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these proxy holders to vote your shares but do not specify how your shares should be voted on a proposal, these proxy holders will vote your shares on such proposals as the IEA board of directors recommends, except if you indicate that you wish to vote against the merger agreement proposal, in which case your shares of IEA common stock will only be voted in favor of the merger-related compensation proposal and the adjournment proposal if you indicate that you wish to vote in favor of such proposals. If any other matter properly comes before the special meeting, these proxy holders will vote on that matter in their discretion.

If, as of the record date, your shares were registered directly in your name with IEA’s transfer agent, Continental Stock Transfer & Trust Company, you are considered the stockholder of record with respect to those shares, and the proxy notice was sent directly to you by IEA. If, as of the record date, your shares were held in an account at a brokerage firm, bank, broker-dealer, or other similar organization, then you are the beneficial owner of shares held in “street name,” and the proxy notice was forwarded to you by that organization. The organization holding your account is considered the stockholder of record for purposes of voting at the special meeting. As a beneficial owner, you must direct your bank, brokerage firm or other nominee on how to vote the shares of IEA common stock held in your account and you will receive instructions from your bank, brokerage firm or other nominee describing how to vote your shares of IEA common stock. The availability of Internet or telephonic voting will depend on the nominee’s voting process. Please check with your bank, brokerage firm or other nominee and follow the voting procedures your bank, brokerage firm or other nominee provides.

If you are a beneficial owner and do not provide your bank, brokerage firm or other nominee instructions on how to vote your shares of IEA common stock with respect to “non-routine” matters, a broker “non-vote” occurs with respect to those matters. Under applicable stock exchange rules, the organization that holds your shares of IEA common stock (i.e., your bank, brokerage firm or other nominee) may generally vote on routine matters at its discretion but cannot vote your shares on “non-routine” matters without your instructions. If you are a beneficial owner and the organization that holds your shares of IEA common stock does not receive instructions from you on how to vote your shares of IEA common stock on a non-routine matter, the organization that holds your shares of IEA common stock will inform the inspector of elections that it does not have the authority to vote your shares on such matters. The merger agreement proposal, the merger-related compensation proposal and the adjournment proposal will be considered “non-routine.” Accordingly, if you are a beneficial owner and do not provide your bank, brokerage firm or other nominee instructions on how to vote your shares of IEA common stock, your bank, brokerage firm or other nominee generally will not be permitted to vote your shares on any of the proposals. If you are a beneficial holder, IEA strongly encourages you to provide voting instructions to your bank, brokerage firm or other nominee so that your vote will be counted on all matters.

If you are a beneficial owner, you are invited to participate in the special meeting; however, you may not vote your shares at the special meeting unless you obtain a legal proxy from your bank, brokerage firm or other nominee that holds your shares giving you the right to vote the shares at the special meeting.

Revocation of Proxies

IEA stockholders of record may revoke their proxies at any time prior to the voting at the special meeting in any of the following ways:

IEA beneficial owners may change their voting instruction only by following the directions received from their bank, brokerage firm or other nominee for changing their voting instructions.

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Solicitation of Proxies

IEA will pay for the proxy solicitation costs related to the special meeting. In addition to sending and making available these materials, some of IEA’s directors, officers and employees may solicit proxies in person by contacting IEA stockholders by telephone or over the Internet. IEA stockholders may also be solicited by press releases issued by IEA, postings on IEA’s websites and advertisements in periodicals. None of IEA’s directors, officers or employees will receive additional compensation for their solicitation services. IEA has engaged D.F. King & Co., Inc. to assist in the solicitation of proxies for the special meeting. IEA estimates that it will pay D.F. King & Co., Inc. a fee of approximately $15,000, plus reasonable out-of-pocket expenses. Certain banking institutions, brokerage firms, custodians, trustees, nominees and fiduciaries who hold shares for the benefit of another party may solicit proxies for IEA. If so, they will mail proxy information to, or otherwise communicate with, the beneficial owners of shares of IEA common stock held by them. IEA will also reimburse banks, brokerage firms, custodians, trustees, nominees and fiduciaries for their expenses incurred in sending proxies and proxy materials to beneficial owners of IEA common stock.

Adjournments

Although it is not currently expected, the special meeting may be adjourned one or more times in accordance with the merger agreement to a later day or time if necessary or appropriate, including to solicit additional proxies in favor of the merger agreement proposal.

In addition to the proposals to (1) adopt the merger agreement and (2) to approve on an advisory (non-binding) basis the compensation that may be paid or become payable to IEA’s named executive officers that is based on or otherwise relates to the merger (referred to as the “merger-related compensation proposal”), IEA stockholders are also being asked to approve a proposal to adjourn the special meeting, from time to time, to a later date or dates, if necessary or appropriate, to solicit additional proxies if there are insufficient votes to adopt the merger agreement at the time of the special meeting. Subject to the limitations on such actions set forth in the merger agreement, the IEA board of directors may cancel, postpone or reschedule any previously scheduled special meeting at any time, before or after the notice for such meeting has been sent to the stockholders. If the special meeting is adjourned or postponed, IEA stockholders who have already submitted their proxies will be able to revoke them at any time before they are voted at the special meeting. Your shares will be voted on any adjournment proposal in accordance with the instructions indicated in your proxy or voting instruction card. The special meeting may be adjourned by the chairman of the meeting, whether or not there is a quorum.

Notice need not be given of any adjourned meeting if the time and place, if any, thereof and the means of remote communications, if any, by which stockholders and proxy holders may be deemed to be present and vote at such adjourned meeting are announced at the meeting at which the adjournment is taken unless the adjournment is for more than 30 days, in which case a notice of the adjourned meeting will be given to each stockholder of record entitled to vote at the meeting. If, after any adjournment, a new record date for the stockholders entitled to vote is fixed for any adjourned meeting, notice of the place, if any, date, and time of the adjourned meeting and the means of remote communications, if any, by which stockholders and proxy holders may be deemed to be present and vote at such adjourned meeting must be given to each stockholder of record entitled to vote at the meeting.

Questions and Additional Information

You may contact IEA’s proxy solicitor, D.F. King & Co., Inc., with any questions about the special meeting, the merger, the proposals or this proxy statement/prospectus, if you would like additional copies of the proxy statement/prospectus, if you need to obtain proxy cards or other information related to the proxy solicitation or if you need help submitting a proxy or voting your shares of IEA common stock. Stockholders may call toll-free at (866) 796-3441, and banks and brokers may call collect at (212) 269-5550.

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PROPOSAL 1: THE MERGER AGREEMENT PROPOSAL

As discussed throughout this proxy statement/prospectus, IEA is asking its stockholders to approve the merger agreement proposal. Pursuant to the merger agreement, Merger Sub will merge with and into IEA, with IEA surviving the merger and becoming a wholly owned subsidiary of MasTec. The merger agreement proposal that IEA is asking its stockholders to approve is the adoption of the merger agreement and approval of the merger. If the merger is completed, IEA will cease to be publicly traded and IEA common stock will be delisted from the Nasdaq Global Select Market and deregistered under the Exchange Act.

As described in further detail in the sections titled “Questions and Answers About the Transaction and Special Meeting,” “Summary – Description of the Transaction and Background of the Transaction” and “The Agreements – Description of the Merger Agreement,” the IEA board of directors has unanimously approved the merger agreement and the merger. For a discussion of certain factors considered by the IEA board of directors in determining to approve the merger agreement and recommend that IEA stockholders vote for the merger agreement proposal, see the section titled “Transaction Summary – IEA’s Reasons for the Transaction and Recommendation of the IEA Board.” A copy of the merger agreement is attached as Annex A to this proxy statement/prospectus. You are urged to read the merger agreement carefully and in its entirety.

The merger is subject to the satisfaction of the conditions set forth in the merger agreement, including approval of the merger agreement proposal by the stockholders of IEA at the special meeting. Accordingly, the approval of the merger agreement proposal by IEA stockholders is a condition to the obligations of MasTec and IEA to complete the merger.

The affirmative vote, virtually or by proxy, of the holders of at least a majority of the outstanding shares of IEA common stock entitled to vote on the merger agreement proposal is required to approve the merger agreement proposal.

THE IEA BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS THAT IEA STOCKHOLDERS VOTE “FOR” THE MERGER AGREEMENT PROPOSAL.

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PROPOSAL 2: THE MERGER-RELATED COMPENSATION PROPOSAL

Pursuant to Section 14A of the Exchange Act and the applicable SEC rules issued thereunder, IEA is required to submit a proposal to approve a resolution, on a non-binding advisory basis, approving the payment of specified compensation that may be paid or become payable to IEA’s named executive officers in connection with the merger. This proposal, commonly known as “say-on-golden parachutes” (referred to as the “merger-related compensation proposal”), gives IEA’s stockholders the opportunity to vote on an advisory and non-binding basis, on the compensation that the named executive officers may be entitled to receive that is based on or otherwise relates to the merger. This compensation is summarized in the table and the footnotes thereto under “Transaction Summary – Interests of IEA’s Directors and Executive Officers in the Transaction – Summary of Potential Transaction Payments to Executive Officers of IEA” beginning on page 69 of this proxy statement.

You should carefully review the golden parachute compensation information disclosed in the sections of this proxy statement/prospectus referred to above. The IEA board of directors unanimously recommends that IEA stockholders approve the following resolution:

RESOLVED, that the stockholders of IEA approve, solely on an advisory, non-binding basis, the golden parachute compensation that will or may be paid or become payable to IEA’s named executive officers in connection with the merger, as disclosed pursuant to Item 402(t) of Regulation S-K in the section titled “Summary of Potential Transaction Payments to Executive Officers of IEA.”

The vote on the merger-related compensation proposal is a vote separate and apart from the vote on the merger agreement proposal. Accordingly, you may vote to approve the merger agreement proposal and vote not to approve the merger-related compensation proposal and vice versa. Because the vote on the merger-related compensation proposal is advisory only, it will not be binding on either IEA or MasTec. Accordingly, if the merger agreement proposal is approved and the merger is completed, the compensation payments that are contractually required to be paid by IEA to its named executive officers will or may be paid or become payable, subject only to the conditions applicable thereto, regardless of the outcome of the non-binding, advisory vote of IEA stockholders on the merger-related compensation proposal.

The affirmative vote of a majority of the votes cast by the stockholders present in person or represented at the special meeting, virtually or by proxy, and entitled to vote on the merger-related compensation proposal, is required to approve, on an advisory (non-binding) basis, the merger-related compensation proposal.

THE IEA BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS THAT IEA STOCKHOLDERS VOTE “FOR” THE MERGER-RELATED COMPENSATION PROPOSAL.

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PROPOSAL 3: THE ADJOURNMENT PROPOSAL

IEA stockholders are being asked to approve the adjournment of the special meeting, if necessary, to solicit additional proxies if there are not sufficient votes to approve the merger agreement proposal at the time of the special meeting.

If you sign and return a proxy and do not indicate how you wish to vote on any proposal, or if you indicate that you wish to vote in favor of the merger agreement proposal but do not indicate a choice on the adjournment proposal, your shares of IEA common stock will be voted in favor of the adjournment proposal. If you indicate, however, that you wish to vote against the merger agreement proposal, your shares of IEA common stock will only be voted in favor of the adjournment proposal if you indicate that you wish to vote in favor of the adjournment proposal. If the special meeting is so adjourned, IEA stockholders who have already submitted their proxies will be able to revoke them at any time prior to their use.

The affirmative vote of holders of at least a majority of the shares of IEA common stock represented at the special meeting, virtually or by proxy, and entitled to vote on the adjournment proposal at the special meeting is required to approve the adjournment proposal.

THE IEA BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS THAT IEA STOCKHOLDERS VOTE “FOR” THE ADJOURNMENT PROPOSAL.

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TRANSACTION SUMMARY

Parties to the Transaction

MasTec, Inc.

MasTec, a Florida corporation, is a leading infrastructure construction company operating mainly throughout North America across a range of industries. MasTec’s primary activities include the engineering, building, installation, maintenance and upgrade of communications, energy, utility and other infrastructure, such as: power delivery services, including transmission and distribution, wireless, wireline/fiber and customer fulfillment activities; power generation, primarily from clean energy and renewable sources; pipeline infrastructure, including natural gas pipeline and distribution infrastructure; heavy civil; and industrial infrastructure. MasTec’s customers are primarily in these industries. Including MasTec’s predecessor companies, MasTec has been in business for over 90 years. For the twelve month period ended June 30, 2022, MasTec had an average of approximately 710 locations and approximately 27,000 employees, and as of June 30, 2022, MasTec had approximately 750 locations and 30,000 employees. MasTec offers its services under the MasTec^® and other service marks. MasTec has been consistently ranked among the top specialty contractors by Engineering News-Record for the past several years.

MasTec’s common stock is listed on the New York Stock Exchange under the symbol “MTZ.” MasTec maintains its principal executive and management office at 800 S. Douglas Road, 12th Floor, Coral Gables, Florida, 33134, and its telephone number is (305) 599-1800. MasTec’s website address is www.mastec.com. MasTec does not intend for information contained on or accessible through its website to be part of this proxy statement/prospectus, other than documents that MasTec files with the SEC that are specifically incorporated by reference in this proxy statement/prospectus.

This proxy statement/prospectus incorporates important business and financial information about MasTec from other documents that are not included in or delivered with this proxy statement/prospectus. For a list of the documents that are incorporated by reference, see “Where You Can Find More Information” beginning on page 115 of this proxy statement/prospectus and “Incorporation of Certain Documents by Reference” beginning on page 113 of this proxy statement/prospectus.

Infrastructure and Energy Alternatives, Inc.

Infrastructure and Energy Alternatives, Inc., a Delaware corporation (referred to as “IEA”) is a holding company that, through various subsidiaries, is a leading diversified infrastructure construction company with specialized energy and heavy civil expertise throughout the United States. IEA was founded in 1947 as White Construction and became a public company in March 2018 when it merged with a special purpose acquisition company. IEA’s common stock trades on The Nasdaq Global Select Market under the symbol ‘‘IEA.’’ The corporate headquarters of IEA are located at 6325 Digital Way, Suite 460, Indianapolis, Indiana 46278, and its telephone number is (800) 688-3775.

Indigo Acquisition I Corp.

Indigo Acquisition I Corp., a Delaware corporation and a wholly owned subsidiary of MasTec, was formed solely for the purpose of consummating the merger of Merger Sub with and into IEA, as provided for in the merger agreement. Merger Sub has not carried on any activities to date, except for activities incidental to its formation and activities undertaken in connection with the transactions contemplated by the merger agreement.

Indigo Acquisition I Corp.’s office is located at 800 S. Douglas Road, 12th Floor, Coral Gables, Florida 33134, and its telephone number is (305) 599-1800.

Description of the Transaction

The following is a description of certain material aspects of the transaction. This description may not contain all of the information that may be important to you. The discussion of the transaction in this proxy

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statement/prospectus is qualified in its entirety by reference to the merger agreement, which is attached to this proxy statement/prospectus as Annex A and the voting agreements, which are attached to this proxy statement/prospectus as Annex B, C and D, respectively. We encourage you to read carefully this entire proxy statement/prospectus, including the Annexes to, and the documents incorporated by reference in, this proxy statement/prospectus and the exhibits to the registration statement to which this proxy statement/prospectus relates, for a more complete understanding of the transaction. This section is not intended to provide you with any factual information about MasTec and IEA. Such information can be found elsewhere in this proxy statement/prospectus and in the public filings MasTec and IEA make with the SEC, as described in “Where You Can Find More Information” beginning on page 115 and “Incorporation of Certain Documents by Reference” beginning on page 113. On July 24, 2022, MasTec entered into a merger agreement with IEA and Merger Sub, pursuant to which Merger Sub will merge with and into IEA, as a result of which, MasTec will acquire IEA.

It is anticipated that, upon the closing of the transaction, the former IEA stockholders will own approximately [●]%, of MasTec’s outstanding shares. The current directors and executive officers of MasTec are expected to remain unchanged. No vote of MasTec stockholders is required in connection with the transaction.

Background of the Transaction

As a part of IEA’s efforts to strengthen its business and enhance stockholder value, the IEA board of directors and senior management of IEA regularly review and assess IEA’s operations, performance, prospects and the strategic landscape in its industry, including the possibility of pursuing various strategic transactions. The review and assessment has included the engagement of legal and financial advisors to assist in considering potential strategic opportunities and alternatives with a view to maximizing IEA stockholder value.

Members of the management teams of each of IEA and MasTec from time to time have met or otherwise communicated informally and independently with each other and with representatives of other infrastructure construction companies and investors regarding industry trends and considerations and the performance, business, strategic direction and prospects of their respective companies.

On September 2, 2021, Quanta Services announced that it was acquiring privately-held Blattner Company, the largest utility-scale renewable energy solutions provider in North America.

On September 7, 2021, MasTec delivered a letter (referred to as the “September 7 Letter”) to JP Roehm, the Chief Executive Officer of IEA, containing a preliminary proposal, based on publicly available information, to combine MasTec and IEA based upon a total enterprise value of IEA of $1.16 billion, which MasTec calculated equated to $16.00 per share of IEA and represented an approximate 8.5x multiple to the Wall Street consensus estimate of IEA’s 2021 Adjusted EBITDA. Mr. Roehm promptly made the letter available to the IEA board of directors. The September 7 Letter noted that MasTec had engaged JPMorgan Chase & Co (referred to as “J.P. Morgan”) as a financial advisor and Fried Frank, Shriver, Harris, Shriver & Jacobson LLP (referred to as “Fried Frank”) as legal counsel and requested that IEA agree to explore a transaction with MasTec on an exclusive basis. The September 7 Letter also highlighted that a definitive transaction agreement would not be subject to any financing condition and that MasTec intended to finance the transaction via existing liquidity sources and/or new debt. IEA’s closing trading price on September 7, 2021 was $13.36 per share.

On September 14, 2021, the IEA board of directors held a meeting which included representatives of IEA management, a financial advisor to IEA (referred to as “Financial Advisor A”) and representatives of Gibson, Dunn & Crutcher LLP, legal counsel to IEA (referred to as “Gibson Dunn”) were present. Representatives of Gibson Dunn discussed with the IEA board of directors its fiduciary duties under applicable law in the context of a potential change of control transaction and in connection with the receipt of the September 7 Letter. Financial Advisor A reviewed the terms of the September 7 Letter as well as preliminary valuation analyses of IEA. The IEA board of directors also discussed the September 7 Letter and potential responses to MasTec.

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On September 17, 2021, the IEA board of directors held a meeting at which representatives of IEA management, representatives of Financial Advisor A and representatives of Gibson Dunn were present. Following continued discussion of the September 7 Letter, the IEA board of directors authorized Mr. Roehm and Mr. Derek Glanvill, the Chairman of the IEA board of directors, to verbally respond to MasTec, indicating that, given IEA’s current strategic plans, IEA was not interested in transacting at the share price indicated in the September 7 Letter proposal, but noting that the IEA board of directors may be willing to consider a different response if MasTec were prepared to pay a fair value for IEA, which the IEA board of directors believed, based on then-recent precedent transactions in the industry and various other factors at such time, was greater than $20 per share.

On September 18, 2021, Messrs. Glanvill and Roehm delivered the message to Mr. José Mas, the Chief Executive Officer of MasTec. Mr. Mas requested that IEA have a discussion with J.P. Morgan to discuss the financial modelling and analysis behind the IEA valuation, and on September 24, 2021, representatives of J.P. Morgan had a call with Mr. Roehm and Mr. Peter Moerbeek, the Chief Financial Officer of IEA, to discuss valuation considerations for IEA. No further discussions were held after the call.

Also during September, MasTec representatives contacted representatives of IEA and Ares Management to discuss the potential transaction, who promptly referred them to Mr. Roehm.

The parties did not enter into a confidentiality agreement at this time and MasTec did not receive any nonpublic materials of IEA at this time.

During the fall and winter of 2021, IEA continued executing its strategic plan and members of the management teams of each of IEA and MasTec from time to time communicated with each other and with representatives of other infrastructure construction companies regarding industry trends and considerations and the performance, business, strategic direction and prospects of their respective companies.

At the end of calendar year 2021, IEA’s closing trading price had decreased to $9.20 per share, reflecting macro trends in the solar industry, and in January 2022, the IEA board of directors decided that IEA should conduct a strategic review to analyze the business and financial condition of IEA and to formulate strategy and develop structural alternatives. On February 1, 2022, the board of directors formally engaged Lazard to assist it in its review.

On February 15, 2022, IEA received an unsolicited, non-binding, indication of interest from a private equity sponsor (referred to as “Sponsor A”) to acquire IEA for a price of $13.00 per share in cash.

On February 22, 2022, Mr. Roehm received a telephone call from a managing director of a private equity sponsor (referred to as “Sponsor B”) indicating that Sponsor B intended to submit a proposal to acquire IEA in an all-cash transaction.

On February 23 and 24, 2022, the IEA board of directors held its regularly scheduled quarterly meeting with representatives of IEA management. Representatives of Lazard attended a portion of the meeting and presented its evaluation of IEA’s strategic plan, as well as various strategic alternatives and growth opportunities.

On March 3, 2022, the IEA board of directors held a meeting at which representatives of IEA management were present. As a follow-up to the February 23 and 24 meeting, the IEA board of directors determined that they would continue to retain Lazard as its financial advisor in connection with IEA’s strategic planning.

On March 4, 2022, IEA received a written, unsolicited, non-binding indication of interest from Sponsor B to acquire IEA for a cash purchase price which Sponsor B estimated would be in the range of a 20% to 40% premium to the volume weighted average price of IEA’s common stock as reported on the NASDAQ Stock Market for the 30-day period ending on March 3, 2022. Based on the calculated $9.44 volume weighted average price of IEA’s common stock as of the time of such letter, Sponsor B’s letter implied an offer price per share of $11.33 to $13.22.

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On March 11, 2022, IEA received an unsolicited, non-binding indication of interest (referred to as the “March 11 Letter”) from MasTec to acquire IEA for a price of $17.00 per share in cash. The March 11 Letter contained other proposed terms and conditions substantially similar to the September 7 Letter. IEA’s closing trading price on March 11, 2022 was $13.10 per share.

On March 23, 2022, representatives of Lazard and Sponsor A discussed the February 15 Letter from Sponsor A. During such discussion, Sponsor A indicated its per share offer price would be increased to $16.00 per share.

On March 28, 2022, the IEA board of directors held a meeting at which representatives of IEA management and Lazard were present. The IEA board of directors, management and Lazard discussed the letters from Sponsor A, Sponsor B and MasTec, as well as a Lazard-prepared preliminary valuation analyses of IEA and updated market dynamics since the February 24 IEA board meeting, noting in particular that between February 24, 2022 and March 28, 2022, IEA’s stock price had traded up approximately 35%. The IEA board of directors and Lazard also discussed considerations regarding a potential strategic outreach process, including potential strategic outreach to counterparties consisting of both strategic acquirors and financial sponsors, as well as alternative paths, including continuing to execute on IEA’s strategic plan and continuing to pursue bolt-on acquisition opportunities.

On March 31, 2022, the IEA board of directors held a meeting at which representatives of IEA management and Lazard were present to further discuss the non-binding indications of interest received. Representatives of Lazard suggested an initial outreach to 13 “tier 1A” parties, which included MasTec, other strategic acquirors, financial sponsors with portfolio companies in the same industry as IEA and other financial sponsors, with potential “tier 1B” parties to contact following the initial outreach. Following discussion, the IEA board of directors instructed Lazard to begin reaching out to the 13 potential “tier 1A” counterparties to solicit interest in participating in a potential strategic outreach process.

Following the March 31 meeting of the IEA board of directors, Lazard began contacting potential counterparties to solicit interest in participating in a potential strategic outreach process. At various points during March, representatives of MasTec contacted representatives of IEA and Ares Management to discuss the potential transaction, who promptly referred them to Mr. Glanvill.

On April 4, 2022, Mr. Roehm and Mr. Glanvill met with Mr. Mas in Miami, Florida for an introductory luncheon meeting.

On April 15, 2022, the IEA board of directors held a meeting at which representatives of IEA management, Lazard and Gibson Dunn were present. Representatives of Gibson Dunn discussed the IEA board of directors’ fiduciary duties in connection with a strategic outreach process, other process and timing considerations and certain terms that would be contained in a draft merger agreement in the event the IEA board of directors decided to engage in negotiations following receipt of indications of interest. Representatives of Lazard provided an update on the strategic outreach process and noted that thirteen potential counterparties, including all of the “tier 1A” counterparties discussed previously with the IEA board of directors, had been contacted, and that five, including MasTec and Sponsor B, had indicated an interest in participating in the strategic outreach process; six parties, including Sponsor A, had declined to participate; and two parties were still considering the opportunity. Sponsor A stated that recent dynamics in its fund after a recent acquisition led to its decision not to participate. Representatives of Lazard also identified additional potential counterparties that had not yet been contacted. Following discussion, the IEA board of directors instructed Lazard to contact such additional potential counterparties, including parties previously identified as “tier 1B” parties.

On April 22, 2022, the IEA board of directors held a meeting at which representatives of IEA management, Lazard and Gibson Dunn were present. Representatives of Lazard provided an update on the strategic process and noted that 24 potential counterparties had been contacted, and that nine, including MasTec and Sponsor B,

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had indicated an interest in participating in the strategic outreach process; nine parties, including Sponsor A, had declined to participate; and six parties were considering the opportunity. Following discussion, the IEA board of directors agreed to move forward with the strategic outreach process with Lazard to finalize a confidential information memorandum and process letter that would be distributed to the interested counterparties and to begin entering into confidentiality agreements with potential counterparties.

On May 5, 2022, the IEA board of directors held a meeting at which representatives of IEA management and Lazard were present. Representatives of Lazard provided an update on the strategic outreach process and noted that 24 potential counterparties had been contacted, and that eleven parties, including MasTec and Sponsor B, had indicated an interest in participating in the strategic outreach process; eleven parties, including Sponsor A, had declined to participate; and two parties were considering the opportunity. The IEA board of directors discussed next steps in the process, expressing a desire to more expeditiously determine if a compelling offer was available, noting the potential distraction of an extended diligence period for multiple bidders, the need to focus on IEA’s strategic plan if a better alternative was not available and the increased leak risk during a prolonged process, which would be detrimental to IEA’s employees and customers. Following discussion, the IEA board of directors agreed that a process letter should be delivered to bidders requesting proposals by June 10, 2022.

Following the meeting of the IEA board of directors on May 5, 2022, one of the eleven potential counterparties that had indicated an interest in participating in the strategic outreach process exited the process.

IEA entered into ten confidentiality agreements with potential bidders, including MasTec. Each confidentiality agreement contained a customary standstill provision which terminated upon the subsequent entry into the merger agreement with MasTec.

On May 13, 2022, Lazard distributed a process letter to each of the ten counterparties. Upon request from MasTec, Lazard also distributed an initial draft merger agreement, prepared by IEA and Gibson Dunn, to MasTec and asked for a complete markup along with the submission of MasTec’s indication of interest.

Each of the ten counterparties was provided access to a virtual dataroom, as well as the management forecasts that were developed in February 2022 in connection with the strategic review planning undertaken by the IEA board of directors, and the opportunity to engage with management regarding due diligence.

On May 25, 2022, representatives of MasTec, including Mr. Mas and Mr. George Pita, the Chief Financial Officer of MasTec, had a financial diligence meeting at a hotel conference room in Indianapolis, Indiana with representatives of IEA management.

On May 26, 2022, the IEA board of directors held a meeting at which representatives of IEA management and Lazard were present. Representatives of Lazard provided an update to the IEA board of directors regarding conversations with potential counterparties, including MasTec, and noted that MasTec was the only counterparty that had requested a draft merger agreement to provide a complete markup in connection with the initial bid and MasTec had also expressed an interest in expediting its diligence process.

On June 3, 2022, MasTec delivered a preliminary non-binding proposal (referred to as the “June 3 Letter”) to acquire IEA at a price of $12.50 per share, together with a revised draft merger agreement. MasTec noted that the proposal, which was based on the financial and other due diligence that had been performed by MasTec, reflected a transaction value of $1.073 billion (exclusive of transaction costs) and represented an approximate 7.7x multiple to MasTec’s estimate of IEA’s 2022 EBITDA of $140 million. The June 3 Letter also noted that as of March 31, 2022, MasTec had liquidity of approximately $1.0 billion and highlighted that a definitive transaction agreement would not be subject to any financing condition. MasTec also requested four weeks of exclusivity.

On June 6, 2022, President Biden issued plans for a 24-month exemption from tariffs for solar panel imports from Cambodia, Malaysia, Thailand and Vietnam. On June 6, 2022, IEA’s stock price closed trading at $9.02, up from $8.10 on June 3, 2022.

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On June 7, 2022, representatives of Lazard spoke to representatives of J.P. Morgan regarding the assumptions underlying the terms of the June 3 Letter, including regarding solar tariffs and MasTec’s views of IEA’s net debt position.

On June 10, 2022, Sponsor B delivered an indicative proposal to acquire IEA for $11.65 per share in cash and to combine IEA with one of Sponsor B’s portfolio companies through a synergistic business combination. On the same day, a private equity sponsor (referred to as “Sponsor C”) submitted a non-binding indication of interest to acquire IEA for a price between $13.00 and $15.00 per share. Also on the same day, a private equity sponsor (referred to as “Sponsor D”) delivered a preliminary, non-binding indication of interest to provide IEA with equity, preferred equity or debt financing alongside a strategic investor. Each of Sponsor B and C highlighted that in-depth due diligence would be required prior to signing a definitive agreement. No other parties submitted a proposal to acquire or invest in IEA.

On June 13, 2022, MasTec delivered an updated non-binding proposal (referred to as the “MasTec Letter”) to acquire IEA for $14.00 per share in cash. MasTec noted that its proposal reflected its current assessment of U.S. economic and regulatory market conditions, including the impact of the recent Presidential executive order regarding solar panel import tariffs.

On June 16, 2022, the IEA board of directors held a meeting at which representatives of IEA management, Lazard and Gibson Dunn were present. Representatives of Lazard reviewed the proposals received from Sponsor B and Sponsor C on June 10, 2022 and the updated MasTec Letter received on June 13, 2022. Representatives of Lazard also summarized the letter from Sponsor D and the discussions with potential counterparties that declined to submit proposals by the June 10 deadline. Lazard noted that it believed that the 24 potential companies Lazard had contacted in the strategic outreach process encompassed the most likely participants in any process to acquire IEA. Representatives of Lazard discussed the due diligence performed to date by each counterparty, noting that MasTec had scheduled and completed four substantive due diligence calls, including regarding legal, accounting and tax, as well as in-person meetings in Indianapolis, Sponsor B and D had each only scheduled and completed one due diligence call, and Sponsor C had not scheduled any due diligence calls. Representatives of Lazard noted that in the current macroeconomic environment, financial sponsors may have difficulty obtaining the necessary debt financing to consummate a transaction, as compared to an investment grade company like MasTec. Lazard also informed the IEA board of directors that based on past experience with Sponsor C, a due diligence process was more likely to move Sponsor C to the bottom end of its range rather than the top end. Representatives of Lazard reviewed a preliminary valuation analysis of IEA based on the forecasts provided to bidders and also shared the results of sensitivity analyses showing potential impact on the valuation analyses if the financial results to be achieved by IEA were below those reflected in management forecasts, including as a result of macroeconomic factors such as supply chain issues, inflation and the recessionary economic environment. Representatives of Gibson Dunn reviewed the terms of the revised merger agreement from MasTec, including a proposed 18-Business Day marketing period, the requirement that stockholders affiliated with Ares Management, Mr. Roehm and Mr. Glanvill enter into a voting agreement with MasTec, and that IEA waive its maximum 32% ownership limitation to allow one of the Ares stockholders to exercise its pre-funded warrants before the record date for the special stockholder meeting, a 4.5% proposed termination fee and revisions to the representations, warranties and covenants. Following discussion of various potential responses to the bidders, the IEA board of directors instructed Lazard to notify MasTec that MasTec did not have the highest offer price and that IEA would move forward with MasTec, on an exclusive basis, to finalize a transaction in the next three weeks if MasTec would increase its offer to $15.50 per share. The IEA board of directors also instructed Lazard to ask MasTec to revise its position on the merger agreement issues highlighted by Gibson Dunn.

On June 17, 2022, representatives of Lazard communicated the message from the IEA board of directors to Mr. Mas, Mr. Pita and representatives of J.P. Morgan.

On June 21, 2022, MasTec delivered an updated non-binding proposal (referred to as the “June 21 Letter”) to acquire IEA for $14.50 per share in cash and noted that MasTec would be willing to include a portion of

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MasTec common stock in the transaction consideration (up to 15% of the total equity purchase price). The June 21 Letter also included a highly confident letter from J.P. Morgan and reiterated MasTec’s requirement that the IEA board of directors waive the Ares stockholders’ ownership limitation to allow one of the Ares stockholders to convert its pre-funded warrants into voting shares prior to the record date for a special meeting to vote on the transaction. The June 21 Letter stated that MasTec would agree to a termination fee between the level proposed in the initial draft from IEA and the amount proposed by MasTec in its markup, and that MasTec will work in good faith to negotiate customary and reasonable representations, warranties and covenants in the definitive agreement. At various points in June, representatives from Ares Management indicated to IEA and MasTec that (i) the Ares stockholder holding pre-funded warrants was unwilling to convert its pre-funded warrants into voting shares and (ii) the voting agreement should terminate upon termination of the merger agreement and upon any change in the IEA board of directors’ recommendation to stockholders.

Later on June 21, 2022, Mr. Mas called Mr. Glanvill to discuss the June 21 Letter. Mr. Glanvill noted that the IEA board of directors would be meeting the next day and that he did not anticipate the IEA board of directors agreeing to move forward exclusively with MasTec based on MasTec’s latest submission.

On June 22, 2022, Mr. Mas called Mr. Glanvill and said that MasTec’s would provide a written best and final offer with a price of $14.75 and that MasTec would require exclusivity to move forward in the process. Later on June 22, 2022, MasTec delivered a letter to IEA consistent with those terms, and otherwise substantially similar to the prior letters, including that MasTec would be willing to include a portion of MasTec common stock in the transaction consideration (up to 15% of the total equity purchase price).

Also on June 22, 2022, representatives of Lazard discussed with representatives of Sponsor C their due diligence completed to date and remaining as well as Sponsor C’s debt financing plans.

Later on June 22 2022, the IEA board of directors held a meeting at which representatives of IEA management, Lazard and Gibson Dunn were present. Mr. Glanvill and representatives of Lazard updated the IEA board of directors on recent discussions with MasTec and Sponsor C, noting that Mr. Mas stated that MasTec’s offer was a best and final price, subject to further due diligence, and that Sponsor C had not yet refined its view on financing and had significant due diligence remaining. Representatives of Gibson Dunn reviewed the IEA board of directors’ fiduciary duties and discussed potential terms that should be included in an exclusivity agreement with MasTec. Representatives of Lazard led a discussion regarding the ability to receive a portion of the consideration in stock and recommended pursuing the all-cash transaction because the price was the same for both offers and if stockholders wished to benefit from the long-term combination of the two companies, stockholders could purchase MasTec shares with their cash merger consideration. Following discussion, the IEA board of directors agreed to move forward with MasTec on an exclusive basis at the current proposed purchase price, subject to negotiation of a definitive execution agreement on customary terms. The IEA board of directors instructed Lazard to notify MasTec and instructed Gibson Dunn to deliver a revised draft merger agreement to MasTec.

On June 23, 2022, representatives of Lazard delivered the IEA board of directors’ message to Mr. Mas and Mr. Pita. Later on June 23, 2022, representatives of Fried Frank delivered a draft exclusivity agreement to representatives of Gibson Dunn.

On June 24, 2022, representatives of Fried Frank told Gibson Dunn that MasTec would be unwilling to incur expenses associated with reviewing a revised draft merger agreement until the exclusivity agreement was executed. Later on June 24, 2022, IEA and MasTec entered into an exclusivity agreement that expired on July 11, 2022. At this time access to the virtual dataroom was limited to MasTec.

Later on June 24, 2022, representatives of Gibson Dunn delivered a revised draft merger agreement to Fried Frank. The revised draft merger agreement deleted the proposed marketing period, provided that any voting agreement would terminate upon termination of the merger agreement and upon any change in the IEA board of

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directors’ recommendation to stockholders, provided that no exercise of warrants would be required pre-closing and proposed a termination fee of 3.0% of implied equity value.

On June 29, 2022, representatives of MasTec, including Mr. Mas and Mr. Pita, had a second in-person financial diligence meeting with representatives of IEA management, including Mr. Roehm and Mr. Moerbeek, at a hotel conference room in Indianapolis, Indiana.

On July 4, 2022, representatives of Fried Frank delivered a revised draft merger agreement which reinserted the 18-Business Day marketing period, required the Ares stockholders holding pre-funded warrants to exercise its pre-funded warrants prior to the special meeting record date, provided that the voting agreements would not terminate on a change of recommendation and proposed a termination fee of 4.0% of implied equity value.

On the evening of July 5, 2022, Mr. Roehm had dinner with MasTec executives and on July 6, 2022, he met with Mr. Mas in his office in Coral Gables, Florida, to continue the financial due diligence process.

On July 6, 2022, representatives of Fried Frank delivered a draft voting agreement to representatives of Gibson Dunn, which Gibson Dunn also transmitted to Paul, Weiss, Rifkind, Wharton & Garrison LLP, legal counsel to the Ares stockholders (referred to as “Paul Weiss”).

On July 7, 2022, Lazard delivered a customary relationship disclosures letter to the IEA board of directors.

Later on July 7, 2022, representatives of Gibson Dunn delivered a revised draft merger agreement to Fried Frank.

On July 8, 2022, the IEA board of directors held a meeting at which representatives of IEA management, Lazard and Gibson Dunn were present. The directors reviewed Lazard’s relationship disclosures letter and determined that none of the disclosed relationships would impact Lazard’s ability to act in an independent and disinterested manner in rendering their services to the IEA board of directors in connection with the potential transaction. As a follow-up to the Lazard June 16, 2022 presentation, IEA management discussed an update to the IEA management forecasts in light of general market conditions impacting IEA and the economy and the industry as a whole. The IEA board of directors discussed the updated forecast and the assumptions underlying the forecast and instructed management to prepare additional materials for discussion at the next meeting of the IEA board of directors. IEA management also provided an update on MasTec due diligence and Gibson Dunn led a discussion of the outstanding issues in the transaction documents. Lazard discussed email correspondence from Mr. Pita communicating that MasTec remained excited about the prospect of a combination with IEA; however, MasTec still needed to complete outstanding financial due diligence.

On July 9, 2022, representatives of IEA management and Gibson Dunn had a call with representatives of MasTec management and Fried Frank to review the draft merger agreement and discuss other transaction documents.

On July 12, 2022, the IEA board of directors held a meeting at which representatives of IEA management, Lazard and Gibson Dunn were present. Representatives of Gibson Dunn provided a summary of the negotiations of the merger agreement and voting agreement and discussed the open issues with the IEA board of directors, including the proposed marketing period, the proposed waiver of the 32% voting restriction and the other terms of the voting agreements. Representatives of IEA management also provided an update on the MasTec due diligence. Representatives of IEA management and Lazard also discussed with the IEA board of directors the proposed updated forecast and answered questions from directors, including regarding the underlying assumptions.

On July 13, 2022, representatives of Fried Frank delivered a revised draft merger agreement to Gibson Dunn.

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On July 13, 2022 and July 14, 2022, Mr. Roehm and Mr. Moerbeek visited MasTec’s offices in Coral Gables, Florida, to meet with MasTec executives, including Mr. Mas and Mr. Pita, to continue financial due diligence. The parties also discussed the communications that would need to be made in connection with the announcement of any transaction.

On July 14, 2022, Mr. Mas called Mr. Glanvill to state that, based on its further financial due diligence, MasTec was struggling with the valuation attributed to IEA at the $14.75 per share amount reflected in the June 22, 2022 Letter. Mr. Mas noted that their internal valuation analyses implied a per share value for IEA lower than $14.75. Mr. Mas also noted that the financing was more expensive than MasTec originally contemplated in their initial offers.

Later on July 14, 2022, Mr. Mas and Mr. Glanvill spoke again and Mr. Glanvill stated that he believed that the IEA board of directors would not be opposed to an offer that included a portion of MasTec stock.

On July 14, 2022, representatives of Gibson Dunn delivered a revised draft voting agreement to Fried Frank incorporating comments from Paul Weiss. Consistent with requests from Paul Weiss and the Ares stockholders, the revised draft deleted the requirement to exercise pre-funded warrants and provided that the voting agreement would terminate upon termination of the merger agreement, a change of recommendation by the IEA board of directors, certain amendments to the merger agreement and upon completion of the IEA special meeting to vote on the merger.

On July 15, 2022, the IEA board of directors held a meeting at which representatives of IEA management, Lazard and Gibson Dunn were present. Mr. Glanvill reported on his discussions with Mr. Mas and Mr. Roehm and provided an update on the financial due diligence meetings in Coral Gables. IEA management then continued the discussions from prior meetings regarding the updated financial forecast, noting that the prior forecast, which had been provided to potential counterparties, was originally prepared in February 2022 and no longer represented management’s best estimates as to future financial performance. IEA management highlighted that the 2022 estimated results were not changed in the updated forecast, but that the series of market disruptions, including the Ukraine war, extended supply chain delays and cost increases and commodity price spikes, and increased cost of capital for customers were expected to reduce the renewables buildouts in the near future, leading to expected margin compression and reduced gross profit and EBITDA over the five-year period. See section entitled “Transaction Summary – IEA Management’s Unaudited Prospective Financial Information” beginning on page 62 of this proxy statement/prospectus for additional details. The IEA board of directors also provided feedback suggesting adjustments to the updated forecasts and agreed that with such changes, the updated forecasts would be approved for use by Lazard in connection with its valuation analyses and provided to MasTec.

Later on July 15, 2022, Mr. Mas called Mr. Glanville and indicated that a revised proposal would be delivered on Monday, July 18, 2022.

Even later on July 15, 2022, the IEA board of directors held a meeting at which representatives of IEA management, Lazard and Gibson Dunn were present. During the meeting, Mr. Glanvill reported on his discussions with Mr. Mas, and the IEA board of directors agreed to reconvene following receipt of the revised offer.

On July 18, 2022, MasTec delivered an updated non-binding proposal to acquire IEA for a price of $13.50 per share in cash or alternatively a price of $14.00 per share, comprised of $10.50 per share in cash with the remainder in the form of MasTec common stock at a fixed exchange ratio to be determined prior to signing. The July 18 letter also noted that MasTec would be providing a draft commitment letter for the bridge financing facility shortly thereafter and that MasTec was prepared to complete the definitive transaction agreements in a few days. Later on July 18, representatives of MasTec delivered a draft of the bridge financing commitment letter to Lazard.

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On July 19, 2022, the IEA board of directors held a meeting at which representatives of IEA management, Lazard and Gibson Dunn were present. Representatives of Lazard reviewed the proposal from MasTec and provided financial and business information regarding MasTec and a comparison to peer companies, including IEA. Representatives of Gibson Dunn discussed implications of accepting a portion of the consideration in stock and, together with Lazard and IEA management, discussed with the IEA board of directors potential upside benefits and considerations of a part cash and part stock consideration. Representatives of Lazard noted that MasTec’s stock price would need to decline by 15% or more in order for the mixed consideration offer to have a value below the all-cash offer. Following discussion, the IEA board of directors instructed IEA management and Lazard to request non-public due diligence information from MasTec, including anticipated Q2 2022 financial results and the impact of an IEA transaction on MasTec guidance for the remainder of fiscal year 2022, as well as information regarding anticipated synergies from the transaction, so the IEA board of directors could reconvene and further assess the potential stock consideration.

Later on July 19, 2022, representatives of Lazard and Mr. Roehm had a call with Mr. Pita to address due diligence questions of the IEA board of directors.

On July 20, 2022, the IEA board of directors held a meeting at which representatives of IEA management, Lazard and Gibson Dunn were present. Representatives of Lazard and IEA management provided an update to the IEA board of directors regarding the due diligence call and the financial information provided by MasTec. Representatives of Lazard discussed the potential upside from the strategic combination of IEA and MasTec and the benefits and potential considerations of a cash and stock transaction compared to the lower all-cash offer. Following discussion the IEA board of directors instructed representatives of Gibson Dunn to deliver a revised draft merger agreement to MasTec that incorporated the necessary changes for a mixed consideration transaction.

Later on July 20, 2022, representatives of Gibson Dunn delivered a revised draft merger agreement to Fried Frank providing for a part cash and part stock merger.

Between July 20, 2022 and July 24, 2022, representatives of Gibson Dunn and Fried Frank, continued to negotiate the terms of the merger agreement and related documentation, including, together with Paul Weiss, the voting agreement.

On July 24, 2022, the IEA board of directors held a meeting at which representatives of IEA management, Lazard and Gibson Dunn were present. Representatives of Lazard reviewed with the IEA board of directors its financial analysis of the merger consideration and delivered to the IEA board of directors its opinion to the effect that, as of that date and based upon and subject to the assumptions, qualifications, limitations and other matters set forth in Lazard’s opinion, the merger consideration to be paid to holders of shares of IEA common stock (other than shares held by holders who are entitled to and properly demand an appraisal of their shares, shares held in the treasury of IEA or owned by any direct or indirect wholly-owned subsidiary of IEA, MasTec or any direct or indirect wholly-owned subsidiary of MasTec and shares held by the Supporting Stockholders (as defined in the merger agreement), in each case at the effective time) in the merger was fair, from a financial point of view, to such holders. Please see the section of this proxy statement entitled “—Opinion of IEA’s Financial Advisor” beginning on page 52 for further description of the opinion and analyses of IEA’s financial advisor. Thereafter, representatives of Gibson Dunn reviewed the proposed merger agreement and discussed the negotiation regarding the marketing period, the voting commitments, the termination fee and other terms and conditions of the merger agreement. Following discussion, the IEA board of directors unanimously determined that the merger agreement and the transactions contemplated thereby, including the merger, were advisable and fair to, and in the best interests of, IEA and its stockholders, and approved and declared advisable the execution, delivery and performance of the merger agreement and the consummation of the transactions contemplated thereby, including the merger, and recommended the adoption of the merger agreement by IEA’s stockholders. For a description of the various factors considered by the IEA board of directors, see the section entitled “Summary – IEA Board Reasons for the Transaction and Recommendation.”

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After the IEA board of directors meeting, IEA and MasTec signed the merger agreement. IEA and MasTec issued a joint press release regarding the transaction before the market open on July 25, 2022.

IEA Board Reasons for the Transaction and Recommendation

At its July 24, 2022 meeting held to evaluate the merger agreement, the IEA board of directors unanimously (i) determined that the terms of the merger agreement and the transactions contemplated thereby, including the merger, are fair to, and in the best interests of, IEA and its stockholders, (ii) determined that it is in the best interests of IEA and its stockholders, and declared it advisable, to enter into the merger agreement, (iii) approved the execution and delivery by IEA of the merger agreement, the performance by IEA of its covenants and agreements contained therein and the consummation of the merger and the other transactions contemplated by the merger agreement upon the terms and subject to the conditions set forth in the merger agreement and (iv) resolved to recommend that the IEA stockholders vote to adopt the merger agreement. The IEA board of directors recommends that IEA stockholders vote:

In evaluating the merger and the merger agreement and arriving at its determination, the IEA board of directors consulted with IEA’s senior management, representatives of IEA’s financial advisor, Lazard, and IEA’s outside legal counsel, Gibson Dunn, and considered a number of substantive factors, both positive and negative, and potential benefits and detriments of the merger to IEA and its stockholders. The IEA board of directors believed that, taken as a whole, the following factors supported its decision to approve the merger:

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The IEA board of directors also considered certain potentially negative factors in its deliberations concerning the merger, including the following:

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The IEA board of directors concluded that the potentially negative factors associated with the merger were significantly outweighed by the potential benefits that it expected the IEA stockholders would achieve as a result of the merger, including the belief of the IEA board of directors that the merger would maximize the immediate value of IEA stockholders’ shares and minimize the risks and uncertainty affecting the future prospects of IEA, including the potential execution risks associated with its stand-alone financial plan. Accordingly, the IEA board of directors unanimously (i) determined that the terms of the merger agreement and the merger are fair to, and in the best interests of, IEA and the IEA stockholders, (ii) determined that it is in the best interests of IEA and the IEA stockholders, and declared it advisable, to enter into the merger agreement, (iii) approved the execution and delivery by IEA of the merger agreement, the performance by IEA of its covenants and agreements contained

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therein and the consummation of the merger upon the terms and subject to the conditions set forth in the merger agreement and (iv) resolved to recommend that the IEA stockholders vote to adopt the merger agreement.

In addition, the IEA board of directors was aware of and considered the interests that IEA’s directors and executive officers may have with respect to the merger that differ from, or are in addition to, the interests of stockholders of IEA generally, as described under “—Interests of IEA’s Directors and Executive Officers in the Transaction.”

The foregoing discussion of the information and factors considered by the IEA board of directors is not exhaustive, but IEA believes it includes all the material factors considered by the IEA board of directors. In view of the wide variety of factors considered in connection with its evaluation of the merger and the complexity of these matters, the IEA board of directors did not consider it practicable to, and did not attempt to, quantify or otherwise assign relative or specific weight or values to any of these factors. Rather, the IEA board of directors viewed its position and recommendation as being based on an overall analysis and on the totality of the information presented to and factors considered by it. In addition, in considering the factors described above, individual directors may have given different weights to different factors. The IEA board of directors based its unanimous recommendation on the totality of the information presented.

This explanation of IEA’s reasons for the merger and other information presented in this section is forward-looking in nature and, therefore, should be read in light of the factors described under “Cautionary Note Regarding Forward-Looking Statements.”

MasTec’s Reasons for the Transaction

The board of directors of MasTec considered a number of factors in making its determination to approve the transaction. These factors include the view of the board of directors of MasTec that the transaction is expected to:

Opinion of IEA’s Financial Advisor

IEA retained Lazard to act as its financial advisor in connection with the merger. In connection with this engagement, the IEA board of directors requested that Lazard evaluate the fairness, from a financial point of view, to holders of IEA common stock (other than excluded holders) of the merger consideration to be paid to such holders in the merger. On July 24, 2022, at a meeting of the IEA board of directors held to evaluate the merger agreement and the merger, Lazard rendered to the IEA board of directors an oral opinion, which was subsequently confirmed in writing by delivery of Lazard’s written opinion, dated as of the same date, to the

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effect that, as of such date, and based upon and subject to the assumptions made, procedures followed, matters considered and qualifications and limitations set forth in Lazard’s written opinion, the merger consideration to be paid to holders of IEA common stock (other than excluded holders) in the merger was fair, from a financial point of view, to such holders.

The full text of Lazard’s written opinion, dated July 24, 2022, which sets forth, among other things, the assumptions made, procedures followed, matters considered and qualifications and limitations on the review undertaken by Lazard in connection with its opinion, is attached to this proxy statement/prospectus as Annex E and is incorporated by reference herein in its entirety. The following summary of Lazard’s opinion is qualified in its entirety by reference to the full text of Lazard’s opinion attached as Annex E. You are encouraged to read Lazard’s opinion and this section carefully and in their entirety.

Lazard’s engagement and its opinion were for the benefit of the IEA board of directors (in its capacity as such), and Lazard’s opinion was rendered to the IEA board of directors in connection with the IEA board of directors’ evaluation of the merger and addressed only the fairness as of the date of the opinion, from a financial point of view, to holders of IEA common stock (other than excluded holders) of the merger consideration to be paid to such holders in the merger. Lazard’s opinion was not intended to, and does not, constitute a recommendation to any stockholder as to how such stockholder should vote or act with respect to the merger or any matter relating thereto. Lazard’s opinion was necessarily based on economic, monetary, market and other conditions as in effect on, and the information made available to Lazard as of, the date of the opinion. Lazard expressed no opinion as to the volatility and disruption in the credit and financial markets relating to, among others, the COVID-19 pandemic and Russia’s invasion of Ukraine and the effects of such volatility or such disruption on IEA. Lazard assumed no responsibility for updating or revising its opinion based on circumstances or events occurring after the date of the opinion. Lazard did not express any opinion as to the prices at which shares of IEA common stock or MasTec common stock may trade at any time subsequent to the announcement of the merger. In addition, Lazard’s opinion did not address the relative merits of the merger as compared to any other transaction or business strategy in which IEA might engage or the merits of the underlying decision by IEA to engage in the merger.

In connection with its opinion, Lazard:

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Lazard assumed and relied upon the accuracy and completeness of the foregoing information, without independent verification of such information. Lazard did not conduct any independent valuation or appraisal of any of the assets or liabilities (contingent or otherwise) of IEA or MasTec or concerning the solvency or fair value of IEA or MasTec, and Lazard was not furnished with any such valuation or appraisal. Management of IEA advised Lazard that the IEA updated management plan was approved by the IEA board of directors and represented as of the date of Lazard’s opinion IEA’s best currently available estimates and judgments as to the future financial performance of IEA and, accordingly, at the direction of IEA, Lazard utilized only the IEA updated management plan for purposes of Lazard’s analysis in connection with its evaluation of the merger and its opinion. With respect to the financial forecasts utilized in Lazard’s analyses, Lazard assumed, with the consent of IEA, that they were reasonably prepared on bases reflecting the best currently available estimates and judgments as to the future financial performance of IEA. Lazard assumed no responsibility for and expressed no view as to any such forecasts or the assumptions on which they were based.

In rendering its opinion, Lazard assumed, with the consent of IEA, that the merger would be consummated on the terms described in the merger agreement, without any waiver or modification of any material terms or conditions. Representatives of IEA advised Lazard, and Lazard assumed, that the merger agreement, when executed, would conform to the draft reviewed by Lazard in all material respects. Lazard also assumed, with the consent of IEA, that obtaining the necessary governmental, regulatory or third-party approvals and consents for the merger would not have an adverse effect on IEA or the merger. Lazard did not express any opinion as to any tax or other consequences that might result from the merger, nor did Lazard’s opinion address any legal, tax, regulatory or accounting matters, as to which Lazard understood that IEA had obtained such advice as it deemed necessary from qualified professionals. Lazard expressed no view or opinion as to any terms or other aspects (other than the merger consideration to the extent expressly specified in the opinion) of the merger, including, without limitation, the form or structure of the merger or any agreements or arrangements entered into in connection with, or contemplated by, the merger, including the Voting Agreements (as defined in the merger agreement) between the Supporting Stockholders and MasTec and any consideration payable to any holder of any Pre-Funded Warrant, Anti-Dilution Warrant, SPAC Warrant or Series B Warrant (each as defined in the merger agreement). In addition, Lazard expressed no view or opinion as to the fairness of the amount or nature of, or any other aspects relating to, the compensation to any officers, directors or employees of any parties to the merger, or class of such persons, relative to the merger consideration or otherwise.

In connection with rendering its opinion, Lazard performed certain financial analyses and reviews of certain information that Lazard deemed appropriate as summarized below under “—Summary of Lazard Financial Analyses,” and Lazard also performed certain additional financial analyses and reviews as summarized below under “—Other Analyses”. The summary of Lazard’s analyses and reviews provided below under “—Summary of Lazard Financial Analyses” and “—Other Analyses” is not a complete description of the analyses and reviews underlying Lazard’s opinion. The preparation of a fairness opinion is a complex process involving various determinations as to the most appropriate and relevant methods of financial analysis and review and the application of those methods to particular circumstances and, therefore, is not readily susceptible to partial analysis or summary description. Considering selected portions of these analyses and reviews or the summary contained in “—Summary of Lazard Financial Analyses” and “—Other Analyses”, without considering the analyses and reviews as a whole, could create an incomplete or misleading view of the analyses and reviews underlying Lazard’s opinion. In arriving at its opinion, Lazard considered the results of all of its analyses and reviews and did not attribute any particular weight to any particular analysis or review or application thereof considered by it; rather, Lazard made its determination as to fairness on the basis of its experience and professional judgment after considering the results of all of its analyses and reviews.

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For purposes of its analyses and reviews, Lazard considered industry performance, general business, economic, market and financial conditions and other matters, many of which are beyond the control of IEA. No company, business or transaction used in Lazard’s analyses and reviews, as a comparison, is identical to IEA or the merger, and an evaluation of the results of those analyses and reviews is not entirely mathematical. Rather, the analyses and reviews involve complex considerations and judgments concerning financial and operating characteristics and other factors that could affect the acquisition, public trading or other values of the companies, businesses or transactions used in Lazard’s analyses and reviews. The estimates contained in Lazard’s analyses and reviews and the ranges of valuations resulting from any particular analysis or review are not necessarily indicative of actual results or values or predictive of future results or values, which may be significantly more or less favorable than those suggested by Lazard’s analyses and reviews. In addition, analyses and reviews relating to the value of companies, businesses or securities do not purport to be appraisals or to reflect the prices at which companies, businesses or securities actually may be sold. Accordingly, the estimates used in, and the results derived from, Lazard’s analyses and reviews are inherently subject to substantial uncertainty.

Lazard was instructed by IEA to use the IEA updated management plan as the basis for its analyses. For purposes of the analyses and reviews described below, as applicable, unless otherwise noted, (a) Lazard assumed, with the consent of and as provided by IEA, net debt of approximately $302 million (as of March 31, 2022, and including $64 million in capital leases, $31 million of proceeds from the exercise of merger warrants, $5 million of proceeds from the exercise of vested options and a negligible amount from the exercise of pre-funded warrants) and approximately 58.7 million fully diluted shares (including 54.8 million diluted shares outstanding, 2.7 million shares issued from merger warrants, 0.8 million anti-dilution warrants and 0.4 million unvested PSUs) and (b) present value date means March 31, 2022. Implied price per share ranges for shares of IEA common stock were rounded to the nearest $0.25.

Summary of Lazard Financial Analyses

The summary of the analyses and reviews provided below includes information presented in tabular format. In order to fully understand Lazard’s analyses and reviews, the tables must be read together with the full text of each summary. The tables alone do not constitute a complete description of Lazard’s analyses and reviews. Considering the data in the tables below without considering the full description of the analyses and reviews, including the methodologies and assumptions underlying the analyses and reviews, could create a misleading or incomplete view of Lazard’s analyses and reviews.

Except as otherwise noted, the following quantitative information, to the extent that it is based on market data, is based on market data as it existed on or before July 22, 2022, and is not necessarily indicative of current market conditions.

Selected Comparable Company Multiples Analysis

Lazard reviewed and analyzed certain financial information, valuation multiples and market trading data related to selected comparable publicly traded specialty engineering and construction (referred to as “E&C”) companies and specialty civil E&C companies whose operations Lazard believed, based on its experience with companies in such industries and its professional judgment, to be generally relevant in analyzing IEA’s operations for purposes of this analysis. Lazard compared such information of the selected comparable companies to the corresponding information for IEA.

The selected group of companies used in this analysis (referred to as the “IEA comparable companies”) was as follows:

Specialty E&C Companies:

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Specialty Civil E&C Companies:

Lazard selected the companies reviewed in this analysis because, among other things, the IEA comparable companies operate businesses similar to the business of IEA. However, no selected company is identical to IEA. Accordingly, Lazard believes that purely quantitative analyses are not, in isolation, determinative in the context of the merger and that qualitative judgments concerning differences between the business, financial and operating characteristics and prospects of IEA and the IEA comparable companies that could affect the public trading values of each company also are relevant.

Lazard calculated and compared various financial multiples and ratios of each of the IEA comparable companies, including, among other things, the ratio of each company’s enterprise value, which Lazard calculated as the market capitalization of each company (based on each company’s closing share price as of July 22, 2022, and fully-diluted share count as of the applicable date specified in its Quarterly Report on Form 10-Q for the most recent fiscal quarter), plus debt, non-controlling interest and preferred or preference stock and less cash, cash equivalents and marketable securities as of the date of each company’s most recent fiscal quarter, to its calendar year 2022 and 2023 estimated earnings before interest, taxes, depreciation and amortization, or “EBITDA,” (which ratio is referred to as the “EBITDA multiple”).

The EBITDA estimates for each of the IEA comparable companies used by Lazard in its analysis were based on public filings and FactSet consensus estimates. The following table summarizes the results of this review:

Specialty E&C Companies:

Specialty Civil E&C Companies:

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Summary Statistics:

Based on an analysis of the EBITDA multiples for each of the IEA comparable companies, as well as its professional judgment and experience, Lazard selected a reference range of 6.75x to 8.75x for the 2022E EBITDA multiple.

Lazard applied such range of EBITDA multiples for the IEA comparable companies to the estimated 2022 EBITDA of IEA, based on estimates provided by IEA in the IEA updated management plan. Lazard’s application of such EBITDA multiples assumed an IEA valuation multiple range in line with IEA’s peers, although Lazard noted that IEA has historically traded below its peers. Lazard averaged the results of these calculations and, from this analysis, estimated an implied value range for shares of IEA common stock.

This analysis resulted in an implied price per share range for shares of IEA common stock, as compared to the per share merger consideration (based on a value as of July 24, 2022 of $14.00 per share, comprised of $10.50 per share in cash and the remainder in the form of MasTec common stock), as set forth below.

Selected Precedent Transactions Multiples Analysis

Lazard reviewed and analyzed selected precedent merger and acquisition transactions involving companies in the industry it viewed as generally relevant in analyzing IEA. In performing this analysis, Lazard reviewed certain financial information and transaction multiples relating to the companies involved in such selected transactions and compared such information to the corresponding information for IEA. Specifically, Lazard selected and reviewed five merger and acquisition transactions announced since 2020 involving companies in the industry for which sufficient information was available.

Lazard reviewed, among other things, the EBITDA multiples of each of the target companies implied by the selected transactions by comparing the enterprise value implied by the acquisition price (excluding any contingent earnout consideration) to the relevant target company’s estimated EBITDA at the time of the transaction for the fiscal year immediately following the fiscal year in which the relevant transaction was announced (referred to as “FY+1”).

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The selected group of transactions reviewed in this analysis and a summary of the results of this review is as follows:

Based on an analysis of the relevant metrics for each of the transactions, as well as its professional judgment and experience, Lazard applied an FY+1 EBITDA multiple range of 6.0x to 10.0x to the 2022 EBITDA estimate of IEA. The 2022 EBITDA estimate for IEA was provided to Lazard by IEA in the IEA updated management plan.

Lazard calculated the low end and high end of the implied price per share of IEA common stock range and, based on that analysis, reviewed the implied price per share range for shares of IEA common stock, as compared to the per share merger consideration, as set forth below:

Discounted Cash Flow Analysis

Lazard performed a discounted cash flow analysis of IEA, which is a valuation methodology used to derive a valuation of a company by calculating the present value of its estimated future cash flows. “Future cash flows” refers to projected unlevered free cash flows of a company. “Present value” refers to the current value of future cash flows or amounts and is obtained by discounting those future cash flows or amounts by a discount rate that takes into account macroeconomic assumptions and estimates of risk, the opportunity cost of capital, capital structure, income taxes, expected returns and other appropriate factors. Lazard calculated the discounted cash flow value for IEA as the sum of the net present value of each of:

The estimated future cash flows were derived from data provided by IEA in the IEA updated management plan, as the IEA updated management plan did not itself provide an explicit calculation of estimated unlevered free cash flows. Lazard calculated “unlevered free cash flow” in this case by beginning with estimated Adjusted EBITDA (defined as EBITDA, adjusted, as applicable, for non-recurring items and any other adjustments, as appropriate), subtracting depreciation and amortization and subtracting stock-based compensation to calculate EBIT; Lazard then applied an income tax rate of 27.0% to calculate after-tax EBIT; Lazard then added back depreciation and amortization, subtracted the year-over-year change in net working capital, added proceeds from the sale of property, plants and equipment, added stock-based compensation and subtracted capital expenditures and other investments. The following table sets forth the estimated unlevered free cash flow for each of fiscal years 2022 through 2027, as used by Lazard for purposes of its discounted cash flow analysis.

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For its discounted cash flow calculations, Lazard applied discount rates ranging from 11.25% to 13.25% using a mid-year convention. Such discount rates were based on Lazard’s judgment and analysis of the estimated range of IEA’s weighted average cost of capital. In calculating the estimated range of weighted average cost of capital for IEA, Lazard used a weighted-average of the estimated cost of equity capital and after-tax costs of debt of 12.11%, assuming a target debt to total capitalization percentage of 37.1%, a marginal tax rate of 27.0% and pre-tax costs of debt of 10.62%. To calculate the estimated cost of equity capital, Lazard used the Capital Asset Pricing Model, which uses a “beta” metric based on the predicted unlevered beta for IEA (1.06), a risk-free rate of return (3.33% based on then-current prevailing yield on the 20-year U.S. Treasury debt) and a market risk premium (7.46% representing the long-horizon expected equity risk premium based on differences of large company stock total returns less long-term government bond income returns, as per the 2021 Duff & Phelps Valuation Handbook—International Guide to Cost of Capital).

The terminal value of IEA was calculated by applying various terminal year Adjusted EBITDA multiples ranging from 6.25x to 8.25x to IEA’s projected terminal year Adjusted EBITDA of $215 million. IEA’s projected terminal year Adjusted EBITDA was calculated by assuming from 2027 onwards a 2.25% EBITDA growth rate; a 2.25% growth rate for depreciation and amortization, change in net working capital and capital expenditures; and flat proceeds from the sale of property, plants and equipment and from stock-based compensation. The terminal year EBITDA multiples were selected by Lazard using its professional judgment and expertise by reference to historic and current EBITDA multiples of IEA comparable companies. The 2022 estimated EBITDA multiples and 2023 estimated EBITDA multiples of IEA comparable companies are set forth above in “—Selected Comparable Company Multiples Analysis.” The resulting range of implied present values of the terminal enterprise values for IEA was calculated based on estimated Adjusted EBITDA multiples for the next twelve-month period (referred to as “NTM”), calculated as a weighted average of the 2022 estimated EBITDA multiples (weighted 25%) and 2023 estimated EBITDA multiples (weighted 75%) of IEA comparable companies.

Lazard took the sum of the present value ranges for IEA’s future cash flows and terminal value to calculate a range of implied enterprise values. Lazard then subtracted the net debt of IEA and calculated a range of implied per share equity values for IEA common stock. Based on that analysis, Lazard reviewed the implied price per share range for shares of IEA common stock as compared to the per share merger consideration as set forth below:

Other Analyses

The analyses and data described below were presented to the IEA board of directors for informational purposes only and did not provide the basis for, and were not otherwise material to, the rendering of Lazard’s opinion.

52-Week High/Low Trading Prices

Lazard reviewed the range of trading prices of shares of IEA common stock for the 52 weeks ended on July 22, 2022, the last full trading day prior to public disclosure of the merger. Lazard observed that, during such period, the daily closing share price of IEA common stock ranged from $6.71 per share to $14.17 per share.

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Research Analyst Price Targets

Lazard reviewed selected equity analyst stock price targets based on publicly available Wall Street equity research reports, which indicated target prices that ranged from $12.00 to $15.00 per share of IEA common stock. The Wall Street equity research reports reviewed by Lazard and price targets set forth in such reports are as follows:

Discounted Cash Flow Sensitivity Analysis—IEA Multiple and IEA Prior Management Plan Cases

Lazard performed an illustrative discounted cash flow sensitivity analysis of IEA using the same methodology as set forth above in “—Discounted Cash Flow Analysis,” except Lazard assumed for the analysis that the terminal year multiple of IEA was illustratively calculated using the historical average of IEA’s NTM EBITDA multiple. In this case, Lazard applied various terminal year Adjusted EBITDA multiples ranging from 4.0x to 5.0x to IEA’s projected terminal year Adjusted EBITDA. The discounted cash flow sensitivity analysis resulted in an implied price per share range for shares of IEA common stock ranging from $9.00 to $12.25.

Lazard also performed two illustrative discounted cash flow sensitivity analyses of IEA using the same procedures and methodologies as set forth above in “—Discounted Cash Flow Analysis,” except Lazard used the IEA prior management plan for the purposes of its analyses. Lazard calculated “unlevered free cash flow” in these cases by beginning with estimated Adjusted EBITDA under the IEA prior management plan, subtracting depreciation and amortization and subtracting stock-based compensation to calculate EBIT; Lazard then applied an income tax rate of 21.5% in 2022 and 26.5% thereafter to calculate after-tax EBIT; Lazard then added back depreciation and amortization, subtracted the year-over-year change in net working capital, added proceeds from the sale of property, plants and equipment, added stock-based compensation and subtracted capital expenditures and other investments. The following table sets forth the estimated unlevered free cash flow under the IEA prior management plan for each of fiscal years 2022 through 2027, as used by Lazard for purposes of these illustrative discounted cash flow sensitivity analyses.

Lazard used the same discount rates as set forth above in “—Discounted Cash Flow Analysis” for its discounted cash flow calculations.

For the first illustrative discounted cash flow sensitivity analysis using the IEA prior management plan, Lazard calculated the terminal value of IEA using the same procedures and methodologies as set forth above in “—Discounted Cash Flow Analysis” for its discounted cash flow calculations. The discounted cash flow sensitivity analysis resulted in an implied price per share range for shares of IEA common stock ranging from $18.25 to $25.50.

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For the second illustrative discounted cash flow sensitivity analysis using the IEA prior management plan, Lazard assumed for the analysis that the terminal value of IEA was illustratively calculated using the historical average of IEA’s NTM EBITDA multiple. In this case, Lazard applied various terminal year Adjusted EBITDA multiples ranging from 4.0x to 5.0x to IEA’s projected terminal year EBITDA. The discounted cash flow sensitivity analysis resulted in an implied price per share range for shares of IEA common stock ranging from $13.25 to $17.25.

Management of IEA advised Lazard that the IEA updated management plan was approved by the IEA board of directors and represented as of July 24, 2022 IEA’s best currently available estimates and judgments as to the future financial performance of IEA; accordingly, at the direction of IEA, Lazard utilized only the IEA updated management plan for purposes of its analyses in connection with its evaluation of the merger and its opinion. As a result, the discounted cash flow analyses utilizing the historical average of IEA’s NTM EBITDA multiple and/or utilizing the IEA prior management plan did not provide the basis for, and were not material to, the rendering of Lazard’s opinion.

Miscellaneous

In connection with Lazard’s services as financial advisor to IEA with respect to the merger, IEA agreed to pay Lazard a fee based on the aggregate consideration involved in the merger, calculated as of immediately prior to the closing of the merger (as of August 25, 2022, such amount was estimated to be approximately $17 million), which is payable contingent upon consummation of the merger. In addition, IEA agreed to pay Lazard a quarterly financial advisory fee of $300,000, beginning on January 1, 2022, 50% of which is creditable against any Transaction fee described above, subject to adjustment by mutual agreement after June 30, 2022. IEA has also agreed to reimburse Lazard for certain expenses incurred in connection with Lazard’s engagement and to indemnify Lazard and certain related persons under certain circumstances against various liabilities that may arise from or be related to Lazard’s engagement, including certain liabilities under United States federal securities laws.

Lazard in the past has provided and currently is providing certain investment banking services to IEA, and certain of its affiliates, for which Lazard has received and may receive compensation, including, during the past two years, having advised IEA on certain strategic planning and financial matters. Lazard in the past has provided certain investment banking services to Ares Management and certain of its affiliates, for which Lazard has received compensation, including, during the past two years, having been engaged to advise (i) Ares Management on its announced expansion of its insurance platform through the launch of Aspida Financial Services, LLC and its 2020 announcement of an agreement by Aspida Holdings Ltd. to acquire F&G Reinsurance Ltd, (ii) funds managed by Ares Management in connection with the 2020 restructuring of their portfolio company, California Resources Corporation, (iii) CS Energy, a portfolio company of funds managed by Ares Management, on its 2021 sale to affiliates of American Securities LLC, (iv) Neiman Marcus Holding Company, Inc., then a portfolio company of funds managed by Ares Management, on its 2020 Chapter 11 restructuring and (v) on certain other non-public engagements in connection with sell-side transactions, fundraising and restructuring advisory. Except as described in this proxy statement/prospectus, the financial advisory business of Lazard has not otherwise received fees for providing services to IEA or MasTec in the two years immediately preceding the date of this proxy statement/prospectus.

Lazard, as part of its investment banking business, is continually engaged in the valuation of businesses and their securities in connection with mergers and acquisitions, negotiated underwritings, secondary distributions of listed and unlisted securities, private placements, leveraged buyouts, and valuations for estate, corporate and other purposes. In addition, in the ordinary course, Lazard and its affiliates and employees may trade securities of IEA, MasTec and certain of their respective affiliates for their own accounts and for the accounts of their customers, may at any time hold a long or short position in such securities, and may also trade and hold securities on behalf of IEA, MasTec and certain of their respective affiliates. The issuance of Lazard’s opinion was approved by the opinion committee of Lazard.

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Lazard is an internationally recognized investment banking firm providing a full range of financial advisory and other services. Lazard was selected to act as investment banker to IEA because of its qualifications, expertise and reputation in investment banking and mergers and acquisitions generally and in the engineering and construction industry specifically, as well as its familiarity with the business of IEA.

IEA and MasTec determined the consideration of (i) $10.50 in cash and (ii) 0.0483 of a share of MasTec common stock per share of IEA common stock, to be paid to the holders of IEA common stock (other than excluded holders) in the merger, through arm’s-length negotiations, and the IEA board of directors unanimously approved such consideration. Lazard did not recommend any specific consideration to the IEA board of directors or any other person or indicate that any given consideration constituted the only appropriate consideration for the merger. Lazard’s opinion was one of many factors considered by the IEA board of directors, as discussed further in “Summary – IEA Board Reasons for the Transaction and Recommendation” on page 48.

IEA Management’s Unaudited Prospective Financial Information

While IEA has from time to time provided limited financial guidance to investors, IEA’s management does not, as a matter of course, otherwise publicly disclose forecasts or internal projections as to future performance due to, among other things, the inherent difficulty of predicting financial performance for future periods and the likelihood that the underlying assumptions and estimates may not be realized. In February 2022, in connection with the IEA board of directors’ strategic review process, IEA prepared certain unaudited non-public financial projections regarding IEA that were delivered to potential counterparties in the strategic outreach process, including MasTec, such financial projections are referred to as the “IEA prior management plan.” In July 2022, IEA updated these unaudited non-public financial projections regarding IEA to take into account changes in the internal and external business environment, including market disruptions resulting in significant changes in economic conditions facing IEA and its industry more generally, including the Ukraine war, increased risk of recession, extended supply chain delays and cost increases, commodity price spikes, persistent high inflation, and the impact of macroeconomic headwinds, such as an increased cost of capital, on IEA’s customers, which was expected to reduce the renewables buildouts in the near future, leading to margin compression and reduced gross profit and EBITDA over the five-year period. The updated unaudited non-public financial projections were delivered to the IEA board of directors and MasTec and are referred to as the “IEA updated management plan”. At the direction of the IEA board of directors, the IEA updated management plan was also provided to, and approved for use by, Lazard for purposes of performing its financial analyses in connection with rendering its opinion to the IEA board of directors (as more fully described in the section titled “—Opinion of IEA’s Financial Advisor”). The IEA prior management plan and the IEA updated management plan are referred to as the “IEA financial projections”.

The IEA financial projections, while presented with numerical specificity, were based on numerous variables and assumptions, including about future performance, that are inherently uncertain and many of which are beyond IEA’s control. The IEA financial projections reflect numerous estimates, assumptions and judgments made by IEA management, based on information available at the time the IEA financial projections were developed, with respect to industry performance and competition, general business, economic, regulatory, market and financial conditions, other future events and matters specific to IEA’s business, all of which are difficult to predict and many of which are beyond IEA’s control. There can be no assurances that the IEA financial projections accurately reflect future trends or accurately estimate IEA’s future financial and operating performance. The IEA financial projections also reflect assumptions as to certain business decisions that are subject to change. Important factors that may affect actual results and cause the IEA financial projections not to be achieved include, but are not limited to, risks and uncertainties relating to IEA’s business (including the ability to achieve strategic goals, objectives and targets over the applicable periods), industry performance, general business and economic conditions and other factors described in or referenced under “Cautionary Note Regarding Forward-Looking Statements” and those risks and uncertainties detailed in IEA’s public filings with the SEC. Further, the IEA financial projections cover multiple years and by their nature become subject to greater uncertainty with each successive year. Modeling and forecasting the future performance of a construction

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company is a highly speculative endeavor. Since the IEA financial projections cover a long period of time, the IEA financial projections by their nature are unlikely to anticipate each circumstance that will have an effect on the value of IEA’s services. Accordingly, there can be no assurance that the IEA financial projections will be realized, and actual results may vary materially from those shown.

The IEA financial projections were not prepared with a view toward public disclosure and, accordingly, do not necessarily comply with guidelines established by the American Institute of Certified Public Accountants for preparation or presentation of prospective financial information and the non-GAAP information used does not comply with generally accepted accounting principles in the United States (referred to as GAAP) but, in the view of IEA management, were prepared on a reasonable basis. The IEA financial projections are not being included in this proxy statement/prospectus to influence any IEA stockholder’s decision as to whether or not to approve the merger or whether or not to seek appraisal rights with respect to shares of IEA common stock held by such stockholder. The summary of the IEA financial projections is being included in this proxy statement/prospectus solely because these IEA financial projections were made available to the IEA board of directors, Lazard and MasTec.

The IEA financial projections do not take into account any circumstances or events occurring after the date they were prepared, including the announcement of the merger and transaction-related expenses. The IEA financial projections also do not take into account the effect of any failure of the merger to close and should not be viewed as accurate or continuing in that context.

The inclusion of the IEA financial projections in this proxy statement/prospectus should not be regarded as an indication that IEA, MasTec or Lazard or any of their respective affiliates, advisors or representatives considered or consider the IEA financial projections to be predictive of actual future events, and the IEA financial projections should not be relied on as such. None of IEA, MasTec or Lazard or any of their respective affiliates, advisors, officers, directors or representatives can give any assurance that actual results will not differ from these IEA financial projections, and none of them undertakes any obligation to update or otherwise revise or reconcile the IEA financial projections to reflect circumstances existing after the date such IEA financial projections were generated or to reflect the occurrence of future events even if any or all of the assumptions underlying the IEA financial projections are shown to be in error or no longer appropriate. Neither IEA nor MasTec intends to make publicly available any update or other revision to the IEA financial projections, except as required by law. None of IEA, MasTec or Lazard or any of their respective affiliates, advisors, officers, directors or representatives has made or makes any representation to any stockholder or other investor regarding the ultimate performance of IEA or MasTec compared to the information contained in the IEA financial projections or that projected results will be achieved.

IEA’s and MasTec’s respective stockholders are cautioned not to place undue reliance on the IEA financial projections included in this proxy statement/prospectus. Neither IEA’s independent auditors, nor any other independent accountants, have compiled, examined, or performed any procedures with respect to the prospective financial information contained herein, nor have they expressed any opinion or any other form of assurance on such information or its achievability, and assume no responsibility for, and disclaim any association with, the prospective financial information.

The IEA financial projections incorporate certain financial measures which are not GAAP measures. Such financial measures should not be considered in isolation from, or as a substitute for, financial information presented in accordance with GAAP. IEA’s calculations of these financial measures may differ from others in its industry and are not necessarily comparable with information presented under similar captions used by other companies. Financial measures provided to a financial advisor are excluded from the SEC’s definition of non-GAAP financial measures and therefore are not subject to SEC rules regarding disclosures of non-GAAP financial measures, which may otherwise require a reconciliation of a non-GAAP financial measure to a GAAP financial measure to be presented. Reconciliations of these financial measures were not relied upon by Lazard for purposes of performing its financial analyses in connection with rendering its opinion to the IEA board of directors (as described in the section titled “—Opinion of IEA’s Financial Advisor”) or by the IEA board of

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directors. Accordingly, a reconciliation of the financial measures included in the IEA financial projections is not provided.

Subject to the foregoing qualifications, the following is a summary of the IEA financial projections:

IEA Prior Management Plan

The following table presents a summary of the IEA financial projections prepared by IEA in February 2022 and provided to potential counterparties in the strategic outreach process.

Adjusted EBITDA represents net income, excluding the impact of income taxes, depreciation and amortization, interest expense and certain other non-cash, non-recurring and/or unusual, non-operating items including, but not limited to, non-cash stock compensation expense, fair value adjustments for warrants, and restructuring expenses.

IEA Updated Management Plan

The following table presents a summary of the IEA financial projections prepared by IEA in July 2022 and, at the direction of IEA, Lazard utilized for purposes of Lazard’s analysis in connection with its evaluation of the merger and its opinion.

Interests of IEA’s Directors and Executive Officers in the Transaction

In considering the recommendation of the IEA board that the IEA stockholders vote to approve the merger, IEA stockholders should be aware that IEA’s directors and executive officers have certain financial interests in

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the merger that may be different from, or in addition to, those of IEA stockholders generally. The IEA board was aware of and considered these potential interests, among other matters, in evaluating and negotiating the merger agreement and the merger and in recommending to the IEA stockholders that they approve the merger. These interests are further described below. In addition, certain directors of IEA are affiliated with entities that are stockholders or warrantholders of IEA.

Equity Awards

The equity awards held by our directors and executive officers will be treated as follows:

Stock Options

Each IEA stock option, whether vested or unvested, that is held by any person (including an executive officer) and that is outstanding immediately prior to the effective time, will, at the effective time, be cancelled and converted into the right to receive: (i) an amount in cash (without interest, and subject to deduction for any required withholding tax) equal to the product of (x) 75% of the excess of $14.00 over the exercise price per share of IEA common stock under such IEA stock option and (y) the number of shares of IEA common stock subject to such IEA stock option, and (ii) a number of shares of MasTec common stock equal to the product of (x) the product of (A) 25% of the excess of $14.00 over the exercise price per share of IEA common stock under such IEA stock option and (B) 0.0138 and (y) the number of shares of IEA common stock subject to such IEA stock option, with any such cash payment to be paid and any such shares of MasTec common stock to be issued to each holder promptly after the effective time, but in any event no later than the fifth business day after the effective time. Any IEA stock option with an exercise price per share as of the effective time that is greater than or equal to $14.00 will be cancelled without any cash payment being made in respect thereof.

The following sets forth, for each IEA executive officer, the aggregate number of shares of IEA Common Stock subject to outstanding IEA options held by such executive officer assuming (i) pursuant to SEC rules, a payment of $14.00 per share, which equals the sum of (A) the cash consideration per share of $10.50 and (B) $3.50 which equals the average closing price of a share of IEA common stock over the first five business days following the first public announcement of the entry into the merger agreement, multiplied by 25%, and (ii) such executive officer remains continuously employed with IEA or a subsidiary until the effective time.

Restricted Stock Units

Each restricted stock unit that is held by any person (including a director or an executive officer) and that vests solely based on the passage of time with respect to shares of IEA common stock, whether vested or unvested, that is outstanding immediately prior to the effective time, will, at the effective time, be cancelled and converted into the right to receive (i) an amount in cash (without interest, and subject to deduction for any required withholding tax) equal to the product obtained by multiplying (x) the cash consideration and (y) the number of shares of IEA common stock subject to such restricted stock unit and (ii) a number of shares of MasTec common stock equal to the product obtained by multiplying (x) the stock consideration and (y) the number of shares of IEA common stock subject to such restricted stock unit, with any such cash payment to be

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paid and any such shares of MasTec common stock to be issued to each holder promptly after the effective time, but in any event no later than the fifth business day after the effective time.

The following sets forth, for each IEA executive officer and director, the aggregate number of shares of IEA Common Stock subject to outstanding IEA time-based restricted stock units held by such executive officer or director and the proceeds thereon, assuming (i) pursuant to SEC rules, a payment of $14.00 per share, which equals the sum of (A) the cash consideration per share of $10.50 and (B) $3.50 which equals the average closing price of a share of IEA common stock over the first five business days following the first public announcement of the entry into the merger agreement, multiplied by 25%, and (ii) such executive officer remains continuously employed with or engaged by IEA or a subsidiary until the effective time:

Performance Stock Units

Each performance stock unit that is held by any person (including an executive officer) and that vests in whole or in part based on the achievement of one or more performance goals with respect to shares of IEA common stock, whether vested or unvested, that is outstanding immediately prior to the effective time, will, at the effective time, be cancelled and converted into the right to receive (i) an amount in cash (without interest, and subject to deduction for any required withholding tax) equal to the product obtained by multiplying (x) the cash consideration and (y) the number of shares of IEA common stock subject to such performance stock unit assuming the target level of performance is achieved and (ii) a number of shares of MasTec common stock equal to the product obtained by multiplying (x) the stock consideration and (y) the number of shares of IEA common stock subject to such performance stock unit assuming the target level of performance is achieved, with any such cash payment to be paid and any such shares of MasTec common stock to be issued to each holder promptly after the effective time, but in any event no later than the fifth business day after the effective time.

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The following sets forth, for each IEA executive officer, the aggregate number of shares of IEA Common Stock subject to outstanding performance-based restricted stock unit award and the proceeds thereon (i) pursuant to SEC rules, a payment of $14.00 per share, which equals the sum of (A) the cash consideration per share of $10.50 and (B) $3.50 which equals the average closing price of a share of IEA common stock over the first five business days following the first public announcement of the entry into the merger agreement, multiplied by 25%, and (ii) such executive officer remains continuously employed with or engaged by IEA or a subsidiary until the effective time:

Severance Arrangements

Each of IEA’s named executive officers, as well as Ms. Roth, has executed an employment agreement with IEA. The employment agreements with Messrs. Roehm, Hanson and Hummer were entered into in connection with IEA’s initial public offering in 2018, and the employments with Messrs. Moerbeek and Stoecker were entered into in order to attract them to IEA and to reflect IEA’s then-existing practice of entering into employment agreements with executives.

Mr. Roehm’s Employment Agreement

In the event that IEA terminates Mr. Roehm’s employment without “cause,” or he terminates employment for “good reason,” within twenty-four (24) months of a “change of control” (which would include the transaction), IEA is required to pay to him three (3) times his then current base salary and three (3) times his Target Bonus Amount, in twelve equal monthly installments during the twelve month period immediately following such termination. Additionally, he is entitled to receive a pro-rata portion of the Target Bonus Amount for the year in which he is terminated. Also, IEA will provide an amount equal to the monthly premium for continued medical, dental and vision coverage, as well as an additional amount sufficient to gross-up Mr. Roehm for any amounts he would recognize as additional income tax attributable to the payment of the premium, payable monthly for a period of twenty-four (24) months, unless the period of coverage is required to be shorter pursuant to federal laws and regulations (“Continuation of Coverage Benefit”). In the event IEA is unable to provide this Continuation of Coverage Benefit beyond an 18-month period, IEA is required to procure and pay for similar insurance coverage for Mr. Roehm and any of his qualifying dependents for the remainder of the 24-month period described above. IEA will additionally pay up to $50,000 for Mr. Roehm’s use of outplacement services.

For purposes of Mr. Roehm’s employment agreement, the following definitions apply:

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Messrs. Moerbeek’s and Stoecker’s Employment Agreements; Ms. Roth’s Employment Agreement

In the event that IEA terminate either Mr. Moerbeek’s or Mr. Stoecker’s employment without “cause,” or either terminates employment for “good reason,” within twenty-four (24) months of a “change of control” (which includes the transaction), IEA is required to pay to either executive two (2) times his then current Base Salary and two (2) times his Target Bonus Amount, in twelve equal monthly installments during the twelve month period immediately following such termination. Additionally, each is entitled to receive a pro-rata portion of the Target Bonus Amount for the year in which he is terminated. Also, IEA will provide an amount equal to the monthly premium for continued medical, dental and vision coverage, as well as an additional amount sufficient to gross-up Mr. Moerbeek or Mr. Stoecker for any amounts he would recognize as additional income tax attributable to the payment of the premium, payable monthly for a period of twenty-four (24) months, unless the period of coverage is required to be shorter pursuant to federal laws and regulations (“Continuation of Coverage Benefit”). In the event IEA is unable to provide this Continuation of Coverage Benefit beyond an 18-month period, IEA is required to procure and pay for similar insurance coverage for each executive and any of his qualifying dependents for the remainder of the 24-month period described above. IEA will additionally pay up to $50,000 for each executive’s use of outplacement services.

For purposes of Messrs. Moerbeek’s and Stoecker’s employment agreements, the definitions of “Cause,” “Good Reason,” “Disability,” and “Target Bonus Amount,” are the same as those applicable to Mr. Roehm’s employment agreement set forth above.

Ms. Roth is party to a substantially-similar employment agreement as Mr. Moerbeek and Mr. Stoecker. Based on the assumptions set forth below, Ms. Roth’s severance entitlement would be cash of $1,480,000 and health continuation and outplacement benefits of $92,913.

Messrs. Hanson’s and Hummer’s Employment Agreements

In the event that IEA terminates Mr. Hanson’s or Mr. Hummer’s employment without “cause,” or either executive terminates employment for “good reason,” IEA is required to pay to each his then current base salary in twelve equal monthly installments during the twelve month period immediately following such termination. Additionally, each is entitled to receive a pro-rata portion of his annual bonus for the year in which he is terminated, assuming the applicable goals are satisfied.

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For purposes of Messrs. Hanson’s and Mr. Hummer’s employment agreements, the definitions of “Cause,” “Good Reason,” and “Disability” are the same as those applicable to Mr. Roehm’s employment agreement.

Indemnification

Executive officers and directors of IEA have rights to indemnification, advancement of expenses and directors’ and officers’ liability insurance that will survive the completion of the transaction.

Summary of Potential Transaction Payments to Executive Officers of IEA

The information set forth below is required by Item 402(t) of Regulation S-K regarding compensation that is based on or otherwise relates to the transaction that IEA’s executive officers could receive in connection with the transaction, as described more fully above under“—Interests of IEA’s Directors and Executive Officers in the Transaction.’’ Such amounts have been calculated assuming (i) the effective time is October 31, 2022, which is the assumed date of closing of the transaction solely for purposes of the disclosures in this section, (ii) a price equal to $14.00, (iii) the annual base salary and annual target bonus opportunity for each of the executive officers remains unchanged from the amount determined as of the date hereof, (iv) none of IEA’s named executive officers receives any additional equity-based awards following the date hereof, (v) each named executive officer is terminated without “Cause” or resigns for “Good Reason” at or immediately following the effective time, (vi) the golden parachute rules under Section 280G of the Code do not limit the payments, and (vii) each of IEA’s named executive officers has properly executed any required releases and complied with all requirements (including any applicable restrictive covenants) necessary in order to receive such payments and benefits. Some of the assumptions used in the table below are based upon information not currently available and, as a result, the actual amounts to be received by any of IEA’s named executive officers, if any, may materially differ from the amounts set forth below. The total payments potentially to IEA’s only other executive officer, totals $2,465,931 using the same assumptions.

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Regulatory Approvals Required for the Merger

The obligations of MasTec and IEA to consummate the transaction are subject to, among other conditions, the expiration or earlier termination of the waiting period (and any extension thereof) under the HSR Act. MasTec and IEA filed the notifications required under the HSR Act with the Premerger Notification Office of the Federal Trade Commission and the Antitrust Division of the Department of Justice on Tuesday August 2, 2022. The applicable waiting period under the HSR Act will expire at 11:59 p.m. Eastern Time on September 1, 2022.

Material U.S. Federal Income Tax Consequences of the Merger

General

The following summary discusses the material U.S. federal income tax consequences of the merger to U.S. Holders and Non-U.S. Holders (each as defined below, and collectively, referred to as the “Holders”). This summary is based on the Code, U.S. Treasury regulations promulgated or proposed thereunder, published rulings by the Internal Revenue Service (referred to as the “IRS”), and judicial authorities and administrative decisions, all as in effect as of the date of this proxy statement/prospectus, and all of which may change, possibly with retroactive effect. Any such changes could affect the accuracy of the statements and conclusions set forth herein. The U.S. federal income tax laws are complex and subject to different interpretations. No ruling has been received from the IRS, and no opinion of counsel has been rendered, as to the U.S. federal income tax consequences of the merger. This summary is not binding on the IRS or a court, and there can be no assurance that the tax consequences described in this summary will not be challenged by the IRS or that they would be sustained by a court if so challenged.

This summary addresses only the consequences of the exchange of shares of IEA common stock held as capital assets within the meaning of Section 1221 of the Code (generally, property held for investment). This discussion is general in nature and does not address all aspects of U.S. federal income taxation that may be

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important to a shareholder in light of that Holder’s particular circumstances, or to a Holder subject to special rules, such as:

If a partnership (including any entity or arrangement treated as a partnership for U.S. federal income tax purposes) is a beneficial owner of shares of IEA common stock, the tax treatment of a partner in such a partnership will generally depend upon the status of the partner and the activities of the partner and the partnership. A partner in a partnership holding shares of IEA common stock should consult its tax advisors regarding the tax consequences of the merger.

This summary of material U.S. federal income tax consequences is not a complete analysis or description of all potential U.S. federal income tax consequences of the merger. In addition, this discussion does not address any alternative minimum tax, non-income tax or state, local or non-U.S. tax consequences of the merger, nor does it address any tax consequences arising under the Foreign Account Tax Compliance Act of 2010 (including the Treasury regulations issued thereunder and intergovernmental agreements entered into pursuant thereto).

Each Holder should consult its own tax advisor to determine the particular tax consequences of the merger to such shareholder in light of such shareholder’s particular circumstances.

U.S. Holders

For purposes of this summary, the term “U.S. Holder” means a beneficial owner of shares of IEA common stock that is, for U.S. federal income tax purposes:

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A U.S. Holder’s receipt of cash and shares of MasTec common stock in exchange for shares of IEA common stock in the merger will be a taxable transaction for U.S. federal income tax purposes. Accordingly, a U.S. Holder generally will recognize gain or loss for U.S. federal income tax purposes in an amount equal to the difference, if any, between (1) the sum of the amount of cash and the fair market value, at the effective time, of the shares of MasTec common stock received by such U.S. Holder in the merger and (2) such U.S. Holder’s adjusted tax basis in the shares of IEA common stock exchanged in the merger.

Any such gain or loss generally will be capital gain or loss and generally will be long-term capital gain or loss if the U.S. Holder’s holding period in the IEA common stock immediately prior to the merger is more than one year. In the case of a U.S. Holder who holds shares of IEA common stock with differing tax bases and/or holding periods, gain or loss must be determined separately for each identifiable block of shares of IEA common stock (generally, shares purchased at the same price in the same transaction). For U.S. Holders that are individuals, estates or trusts, long-term capital gain generally is taxed at preferential rates. The deductibility of capital losses is subject to limitations. Each U.S. Holder is urged to consult its tax advisor regarding the manner in which gain or loss should be calculated as a result of the merger.

In addition to regular U.S. federal income tax, certain U.S. Holders that are individuals, estates or trusts are subject to a 3.8% tax on all or a portion of their “net investment income,” which may include all or a portion of any gain or loss realized by such U.S. Holder.

A U.S. Holder will have a tax basis in the shares of MasTec common stock received in the merger equal to the fair market value of such shares at the effective time. The holding period for shares of MasTec common stock received in exchange for shares of IEA common stock in the merger will begin on the date immediately following the closing date.

Non-U.S. Holders

For purposes of this summary, the term “Non-U.S. Holder” means a beneficial owner of shares of IEA common stock that is neither a U.S. Holder nor an entity or arrangement treated as a partnership for U.S. federal income tax purposes.

Any gain realized by a Non-U.S. Holder pursuant to the merger generally will not be subject to U.S. federal income tax unless:

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Backup Withholding and Information Reporting

A U.S. Holder generally will be subject to information reporting with respect to the proceeds received by such U.S. Holder in the merger. In addition, a U.S. Holder may, under certain circumstances, be subject to backup withholding (currently at a rate of 28%) on the proceeds to which such U.S. Holder is entitled in connection with the merger, unless such U.S. Holder provides the appropriate documentation (generally, a properly completed IRS Form W-9) to the applicable withholding agent certifying that, among other things, its taxpayer identification number is correct, or otherwise establishes an exemption from backup withholding.

The information reporting and backup withholding rules that apply to payments to a U.S. Holder generally will not apply to payments to a Non-U.S. Holder in connection with the merger if such Non-U.S. Holder certifies under penalties of perjury that it is not a U.S. person (generally by providing a properly completed IRS Form W-8BEN or W-8BEN-E) and satisfies certain other requirements or otherwise establishes an exemption. Non-U.S. Holders should consult their own tax advisors regarding these matters.

Backup withholding is not an additional tax. Any amounts withheld from a Holder under the backup withholding rules will generally be allowable as a refund or credit against such Holder’s U.S. federal income tax liability, provided that certain required information is timely furnished to the IRS and other applicable requirements are satisfied.

The preceding summary is provided for general informational purposes only and is neither tax advice nor a complete analysis or discussion of all potential tax consequences of the merger relevant to shareholders. Each Holder should consult its own tax advisor to determine the particular tax consequences of the merger to such shareholder in light of such Holder’s particular circumstances.

Accounting Treatment of the Transaction

The merger of MasTec and IEA will be accounted for under the acquisition method of accounting in accordance with ASC 805, and MasTec will be treated as the acquirer of IEA for accounting purposes. Accordingly, MasTec will allocate IEA’s purchase price to the acquired tangible and intangible assets and liabilities of IEA based upon their estimated fair values as of the acquisition date. Any excess purchase price will be recorded as goodwill. No pro forma financial information is included in this document because the acquisition is not significant to MasTec under the rules of the SEC.

Financing of the Transaction

On July 24, 2022, in connection with the merger agreement, MasTec entered into the debt commitment letters with Bank of America and JPMorgan with respect to the financing required by IEA to consummate the merger.

The financing under the debt commitment letters provides for credit facilities in an aggregate principal amount of up to $1.0 billion, consisting of: (i) an agreement to arrange senior unsecured delayed draw term loan facilities in an aggregate principal amount of up to $1.0 billion, of which the Commitment Parties have committed to provide up to $230 million and/or (ii) a commitment to provide 364-day senior unsecured bridge loan facility in an aggregate principal amount of up to $1.0 billion. The commitments under the Bridge Facility shall be reduced on a dollar-for-dollar basis by, among other things, the commitments under the Term Loan Facilities outstanding on the effective date of the Term Loan Facilities documentation.

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MasTec and MasTec North America, Inc. will be co-borrowers under the Credit Facilities. Pursuant to the debt commitment letters, BANA agreed to act as the administrative agent, JPMorgan agreed to act as sole syndication agent, and BofA Securities and JPMorgan agreed to act as joint lead arrangers and joint bookrunners for each of the Credit Facilities on the terms and subject to the conditions set forth therein. The covenants, defaults, prepayments, and guarantees for the Credit Facilities are expected to be substantially similar to those under the Amended Existing Credit Agreement, except as otherwise set forth in the debt commitment letters. Each of the Credit Facilities will bear interest at SOFR plus an applicable margin. The Credit Facilities will be unsecured and, so long as the Existing Credit Agreement is amended to remove the guarantee requirements (as described below), will not be guaranteed by any of MasTec’s subsidiaries. Various economic and other terms of the credit facilities are subject to change in the process of syndication.

In connection with the transaction, on August 8, 2022, MasTec commenced an offer to eligible holders of the IEA Notes to exchange any and all of the outstanding IEA Notes for up to an aggregate principal amount of $300 million of new 6.625% Senior Notes due 2029 to be issued by MasTec. Concurrently with the Exchange Offer, MasTec is soliciting consents with respect to the IEA Notes to eliminate or modify certain of the covenants, restrictive provisions and events of default in the existing indenture governing the IEA Notes. Neither the Exchange Offer nor the Consent Solicitation is required by IEA to consummate the merger, and the consummation of each is conditioned upon the consummation of the merger. MasTec may complete the Exchange Offer regardless of whether it completes the Consent Solicitation. This proxy statement/prospectus does not constitute an offer to sell or the solicitation of an offer to buy any debt securities of MasTec, IEA or the IEA Issuer. It does not constitute a prospectus or prospectus equivalent document for any such securities. No offering of any debt securities of MasTec, IEA or the IEA Issuer shall be made except by means of a prospectus meeting the requirements of Section 10 of the Securities Act or an exemption therefrom.

MasTec is also seeking to amend its Existing Credit Agreement, to, among other things, release the existing guarantees thereof and remove the existing requirement that certain subsidiaries guarantee the obligations thereunder.

The debt commitment letters contain conditions to funding of the debt financing customary for commitments of this type, including but not limited to:

Appraisal Rights

General. Holders of IEA common stock will become holders of MasTec common stock as a result of the merger. Holders of IEA common stock will be entitled to appraisal rights under Section 262 of the DGCL in connection with the merger.

If you hold one or more shares of IEA common stock, you are entitled to appraisal rights under Delaware law and have the right to have your shares appraised by the Delaware Court of Chancery and receive the “fair value” of such shares (exclusive of any element of value arising from the accomplishment or expectation of the

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merger) as of completion of the merger in place of the merger consideration, as determined by the court, if you strictly comply with the procedures specified in Section 262 of the DGCL. Any such IEA stockholder awarded “fair value” for its, his or her shares by the court would receive payment of that fair value in cash, together with interest, if any, in lieu of the right to receive the merger consideration.

The following discussion is not a full summary of the law pertaining to appraisal rights under the DGCL and is qualified in its entirety by the full text of Section 262 of the DGCL that is attached to this proxy statement/prospectus as Annex F. All references in Section 262 of the DGCL and in this summary to a “stockholder” are to the record holder of the shares of IEA common stock. The following discussion does not constitute any legal or other advice, nor does it constitute a recommendation that you exercise your rights to seek appraisal under Section 262 of the DGCL.

Under Section 262 of the DGCL, when a merger is submitted for approval at a meeting of stockholders as in the case of approval of the merger agreement proposal, IEA, not less than 20 days prior to the meeting, must notify each stockholder who was an IEA stockholder on the record date for notice of such meeting with respect to shares for which appraisal rights are available, that appraisal rights are available and include in the notice a copy of Section 262 of the DGCL. This proxy statement/prospectus constitutes the required notice, and the copy of Section 262 of the DGCL is attached to this proxy statement/prospectus as Annex F. A holder of IEA common stock who wishes to exercise appraisal rights or who wishes to preserve the right to do so should review the following discussion and Annex F carefully and consult with legal advisors. Failure to strictly comply with the procedures of Section 262 of the DGCL in a timely and proper manner may result in the loss of appraisal rights under the DGCL. A stockholder who loses his, her or its appraisal rights will be entitled to receive the merger consideration.

How to Exercise and Perfect Your Appraisal Rights. IEA stockholders wishing to exercise the rights to seek an appraisal of their shares must do ALL of the following:

Voting, virtually or by proxy, against, abstaining from voting on or failing to vote on the approval of the merger agreement proposal will not constitute a written demand for appraisal as required by Section 262 of the DGCL. The written demand for appraisal must be in addition to and separate from any proxy or vote.

Who May Exercise Appraisal Rights. A demand for appraisal must be executed by or on behalf of the stockholder of record. The demand should set forth, fully and correctly, the stockholder’s name as it appears on

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the stock certificates (or in the stock ledger). The demand must reasonably inform IEA of the identity of the stockholder and that the stockholder intends to demand appraisal of his, her or its common stock. Non-record owners may not directly make appraisal demands to IEA. The non-record owner must, in such cases, have the owner of record, such as a bank, brokerage firm or other nominee, submit the required demand in respect of those shares of common stock. A record owner, such as a bank, brokerage firm or other nominee, who holds shares of IEA common stock as a nominee for others, may exercise appraisal rights with respect to the shares of IEA common stock held for one or more non-record owners, while not exercising this right for other non-record owners. In that case, the written demand should state the number of shares of IEA common stock as to which appraisal is sought. Where no number of shares of IEA common stock is expressly mentioned, the demand will be presumed to cover all shares of IEA common stock held in the name of the record owner.

IF YOU HOLD YOUR SHARES IN BANK OR BROKERAGE ACCOUNTS OR OTHER NOMINEE FORMS, AND YOU WISH TO EXERCISE APPRAISAL RIGHTS, YOU SHOULD CONSULT WITH YOUR BANK, BROKERAGE FIRM OR OTHER NOMINEE, AS APPLICABLE, TO DETERMINE THE APPROPRIATE PROCEDURES FOR THE BANK, BROKERAGE FIRM OR OTHER NOMINEE TO MAKE A DEMAND FOR APPRAISAL OF THOSE SHARES. IF YOU HAVE A BENEFICIAL INTEREST IN SHARES HELD OF RECORD IN THE NAME OF ANOTHER PERSON, SUCH AS A BANK, BROKERAGE FIRM OR OTHER NOMINEE, YOU MUST ACT PROMPTLY TO CAUSE THE RECORD HOLDER TO FOLLOW PROPERLY AND IN A TIMELY MANNER THE STEPS NECESSARY TO PERFECT YOUR APPRAISAL RIGHTS.

If you own shares of IEA common stock jointly with one or more other persons, as in a joint tenancy or tenancy in common, demand for appraisal must be executed by or for you and all other joint owners. An authorized agent, including an agent for two or more joint owners, may execute the demand for appraisal for a stockholder of record; however, the agent must identify the record owner and expressly disclose the fact that, in making the demand, such person is acting as agent for the record owner. If you hold shares of IEA common stock through a broker who in turn holds the shares through a central securities depository nominee such as Cede & Co., a demand for appraisal of such shares must be made by or on behalf of the depository nominee and must identify the depository nominee as record holder.

If you elect to exercise appraisal rights under Section 262 of the DGCL, you should mail or deliver a written demand, executed as set forth above, to:

INFRASTRUCTURE AND ENERGY ALTERNATIVES, INC.

6325 Digital Way, Suite 460

Indianapolis, Indiana 46278

(800) 688-3775

Attention: Secretary

Actions After Completion of the Merger. If the merger is consummated, the surviving company in the merger will give written notice that the merger has become effective within 10 days after the effective time of the merger to each stockholder that did not vote in favor of the merger agreement and delivered a written demand for appraisal in accordance with Section 262 of the DGCL. At any time within 60 days after the effective time of the merger, any stockholder that did not commence an appraisal proceeding or join in such a proceeding as a named party will have the right to withdraw such demand and to accept the merger consideration in accordance with the merger agreement for his, her or its shares of common stock. Within 120 days after the effective time of the merger, but not later, any stockholder that has complied with the requirements of Section 262 of the DGCL, or the surviving company in the merger, may commence an appraisal proceeding by filing a petition in the Delaware Court of Chancery, with a copy served on the surviving company in the merger in the case of a petition filed by a stockholder, demanding a determination of the value of the shares of IEA common stock held by all such stockholders. The surviving company in the merger is under no obligation to file an appraisal petition and has no intention of doing so. If you desire to have your shares appraised and have otherwise complied with the

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requirements of Section 262 of the DGCL, you should initiate any petitions necessary for the perfection of your appraisal rights within the time periods and in the manner prescribed in Section 262 of the DGCL.

Within 120 days after the effective time of the merger, any stockholder that has complied with the provisions of Section 262 of the DGCL will be entitled to receive from the surviving company in the merger, upon written request, a statement setting forth the aggregate number of shares not voted in favor of the approval of the merger agreement proposal and with respect to which IEA has received demands for appraisal, and the aggregate number of holders of those shares. The surviving company in the merger must mail this statement within the later of 10 days of receipt by the surviving company in the merger of the request therefor or 10 days after expiration of the period for delivery of demands for appraisal. If you are the non-record owner of shares of stock held in a voting trust or by a nominee on your behalf, you may, in your own name, file an appraisal petition or request from the surviving company in the merger the statement described in this paragraph.

If a petition for appraisal is duly filed, and a copy of the petition is delivered to the surviving company in the merger, the surviving company in the merger will then be obligated, within 20 days after receiving service of a copy of the petition, to provide the Delaware Register in Chancery with a duly verified list containing the names and addresses of all holders who have demanded an appraisal of their shares. The Delaware Court of Chancery will then determine which stockholders are entitled to appraisal rights and may require the stockholders demanding appraisal who hold certificated shares to submit their stock certificates to the Register in Chancery for notation thereon of the pendency of the appraisal proceedings and the Delaware Court of Chancery may dismiss the proceedings as to any stockholder who fails to comply with this direction. Where proceedings are not dismissed or the demand for appraisal is not successfully withdrawn, the appraisal proceeding will be conducted as to the shares of IEA common stock owned by such stockholders in accordance with the rules of the Delaware Court of Chancery, including any rules specifically governing appraisal proceedings. The Delaware Court of Chancery will thereafter determine the fair value of the shares of IEA common stock at the effective time of the merger held by all stockholders who have properly perfected appraisal rights, exclusive of any element of value arising from the accomplishment or expectation of the merger. Unless the Delaware Court of Chancery in its discretion determines otherwise for good cause shown, interest from the effective time of the merger through the date of payment of the judgment will be compounded quarterly and will accrue at 5% over the Federal Reserve discount rate (including any surcharge) as established from time to time during the period between the effective time of the merger and the date of payment of the judgment. When the value is determined, the Delaware Court of Chancery will direct the payment of such value, with interest thereon, if any, to the stockholders entitled to receive the same, upon surrender by such stockholders of their stock certificates or, in the case of book-entry shares, forthwith.

In determining the fair value, the Delaware Court of Chancery is required to take into account all relevant factors. In Weinberger v. UOP, Inc., the Delaware Supreme Court discussed the factors that could be considered in determining fair value in an appraisal proceeding, stating that “proof of value by any techniques or methods which are generally considered acceptable in the financial community and otherwise admissible in court” should be considered and that “[f]air price obviously requires consideration of all relevant factors involving the value of a company.” The Delaware Supreme Court has stated that, in making this determination of fair value, the court must consider market value, asset value, dividends, earnings prospects, the nature of the enterprise and any other factors which could be ascertained as of the date of the merger which throw any light on future prospects of the merged corporation. Section 262 of the DGCL provides that fair value is to be “exclusive of any element of value arising from the accomplishment or expectation of the merger.” In Cede & Co. v. Technicolor, Inc., the Delaware Supreme Court stated that such exclusion is a “narrow exclusion [that] does not encompass known elements of value,” but which rather applies only to the speculative elements of value arising from such accomplishment or expectation. In Weinberger, the Delaware Supreme Court construed Section 262 of the DGCL to mean that “elements of future value, including the nature of the enterprise, which are known or susceptible of proof as of the date of the merger and not the product of speculation, may be considered.” An opinion of an investment banking firm as to the fairness from a financial point of view of the consideration payable in a merger is not an opinion as to, and does not in any manner address, fair value under Section 262 of the DGCL. The fair value of

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your shares as determined under Section 262 of the DGCL could be greater than, the same as, or less than the value of the merger consideration. MasTec and the surviving company in the merger do not anticipate offering more than the merger consideration to any stockholder exercising appraisal rights and reserve the right to assert, in any appraisal proceeding, that, for purposes of Section 262, the “fair value” of a share of IEA common stock is less than the merger consideration.

If no party files a petition for appraisal within 120 days after the effective time of the merger, then all stockholders will lose the right to an appraisal, and will instead receive the merger consideration described in the merger agreement, without interest thereon.

The Delaware Court of Chancery may determine the costs of the appraisal proceeding and may tax those costs against the parties as the Delaware Court of Chancery deems to be equitable under the circumstances. However, costs do not include attorneys and expert witness fees. Each stockholder is responsible for its own attorneys and expert witnesses expenses, although, upon application of a stockholder, the Delaware Court of Chancery may order all or a portion of the expenses incurred by any stockholder in connection with the appraisal proceeding, including reasonable attorneys’ fees and the fees and expenses of experts, to be charged pro rata against the value of all shares entitled to appraisal.

Any stockholder that has duly demanded an appraisal in compliance with Section 262 of the DGCL will not, after the effective time of the merger, be entitled to vote the IEA shares subject to that demand for any purpose or receive any dividends or other distributions on those shares, except dividends or other distributions payable to holders of record of IEA shares as of a record date prior to the effective time of the merger.

Any stockholder that has not commenced an appraisal proceeding or joined such a proceeding as a named party may withdraw a demand for appraisal and accept the merger consideration by delivering a written withdrawal of the demand for appraisal to the surviving corporation, except that any attempt to withdraw made more than 60 days after the effective time of the merger will require written approval of the surviving company in the merger. No appraisal proceeding in the Delaware Court of Chancery will be dismissed as to any stockholder without the approval of the Delaware Court of Chancery and such approval may be conditioned on the terms the Delaware Court of Chancery deems just, provided, however, that this provision will not affect the right of any stockholder who has not commenced an appraisal proceeding or joined such proceeding as a named party to withdraw such stockholder’s demand for appraisal and to accept the terms offered in the merger within 60 days after the effective time of the merger. If you fail to perfect, successfully withdraw or lose the appraisal right, your shares will be converted into the right to receive the merger consideration, without interest thereon.

Failure to follow the steps required by Section 262 of the DGCL for perfecting appraisal rights may result in the loss of appraisal rights. In that event, you will be entitled to receive the merger consideration for your shares in accordance with the merger agreement. In view of the complexity of the provisions of Section 262 of the DGCL, if you are an IEA stockholder and are considering exercising your appraisal rights under the DGCL, you should consult your own legal advisor.

THE PROCESS OF DEMANDING AND EXERCISING APPRAISAL RIGHTS REQUIRES STRICT COMPLIANCE WITH TECHNICAL PREREQUISITES. IF YOU WISH TO EXERCISE YOUR APPRAISAL RIGHTS, YOU SHOULD CONSULT WITH YOUR OWN LEGAL COUNSEL IN CONNECTION WITH COMPLIANCE UNDER SECTION 262 OF THE DGCL. TO THE EXTENT THERE ARE ANY INCONSISTENCIES BETWEEN THE FOREGOING SUMMARY AND SECTION 262 OF THE DGCL, THE DGCL WILL GOVERN.

Listing of MasTec Shares to be Issued in the Merger

MasTec will use reasonable best efforts to cause the MasTec common stock issuable in the transactions to be authorized for listing on the NYSE, subject to official notice of issuance, prior to the closing date. MasTec

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will also use its reasonable best efforts to obtain all necessary state securities law or “blue sky” permits and approvals required to carry out the transactions contemplated by the merger agreement.

Delisting and Deregistration of IEA Common Stock and IEA SPAC Warrants

To the extent requested by MasTec, prior to the closing, IEA will cooperate with MasTec and use its reasonable best efforts to take, or cause to be taken, all actions, and do or cause to be done, all things, reasonably necessary, proper or advisable on its part under applicable laws and rules and policies of the Nasdaq to enable the de-listing by the surviving corporation of the shares of IEA common stock from the Nasdaq as promptly as practicable after the effective time and the deregistration of the IEA common stock under the Exchange Act at the effective time.

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THE AGREEMENTS

The following summary describes certain material provisions of the merger agreement and the voting agreements entered into in connection with the transaction, and is qualified in its entirety by reference to those agreements. Copies of the merger agreement and the voting agreements are attached to this proxy statement/prospectus as Annexes A, B, C and D, respectively, and are incorporated by reference into this proxy statement/prospectus. The voting agreements are filed as exhibits to the registration statement to which this proxy statement/prospectus relates and are incorporated by reference into this proxy statement/prospectus. This summary may not contain all of the information about the agreements that may be important to you. We encourage you to carefully read each of the agreements in its entirety for a more complete understanding of the transaction.

Description of the Merger Agreement

This section of this proxy statement/prospectus describes certain material terms of the merger agreement. The following summary is qualified in its entirety by reference to the complete text of the merger agreement, which is incorporated by reference and attached as Annex A to this proxy statement/prospectus. We urge you to read the entire merger agreement.

The merger agreement and the discussion under the heading “The Agreements—Description of the Merger Agreement” have been included to provide you with information regarding the terms of the merger agreement. They are not intended to provide any other factual information about IEA, MasTec or Merger Sub. That information can be found elsewhere in this proxy statement/prospectus and in the other public filings made by IEA and MasTec with the SEC, which are available without charge at www.sec.gov. See “Where You Can Find More Information” beginning on page 115 and “Incorporation of Certain Documents by Reference” beginning on page 113.

On July 24, 2022, MasTec entered into the merger agreement with IEA and Merger Sub. The merger agreement provides, among other things, for the merger of Merger Sub with and into IEA with IEA surviving the merger as a wholly-owned subsidiary of MasTec and the issuance to IEA stockholders of shares of MasTec common stock and cash as described below in “The Agreements – Transaction Structure – Consideration in the Merger.”

Transaction Structure

The parties do not intend that the consummation of the transactions contemplated by the merger agreement, including the merger, will require a vote of the holders of MasTec common stock, and each of IEA and MasTec will use reasonable best efforts to avoid taking any action that would reasonably be expected to require such vote to be obtained.

Closing of the Transaction

The closing of the transaction will take place at 9:00 a.m. Eastern Time in New York City on the third business day after the satisfaction or, to the extent permitted by applicable law, waiver of the conditions set forth in the merger agreement (other than those conditions that by their nature are to be satisfied at the closing, but subject to the satisfaction of such conditions or, to the extent permitted by applicable law, waiver of such conditions), unless another date, time or place is agreed to in writing by MasTec and IEA; provided that, the closing will not occur sooner than September 22, 2022.

Consideration in the Merger

In the merger, each share of IEA common stock issued and outstanding immediately prior to the merger will automatically be converted into the right to receive (i) $10.50 in cash, without interest and (ii) 0.0483 of a validly issued, fully paid and nonassessable share of MasTec common stock.

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IEA stockholders are entitled to appraisal rights under the DGCL in connection with the merger only to the extent described herein. See “Appraisal Rights” beginning on page 74.

Treatment of Stock Options, Warrants and Other Equity-Based Awards

Stock Options

Each IEA stock option, whether vested or unvested, that is outstanding immediately prior to the effective time, will, at the effective time, be cancelled and converted into the right to receive: (i) an amount in cash (without interest, and subject to deduction for any required withholding tax) equal to the product of (x) 75% of the excess of $14.00 over the exercise price per share of IEA common stock under such IEA stock option and (y) the number of shares of IEA common stock subject to such IEA stock option, and (ii) a number of shares of MasTec common stock equal to the product of (x) the product of (A) 25% of the excess of $14.00 over the exercise price per share of IEA common stock under such IEA stock option and (B) 0.0138 and (y) the number of shares of IEA common stock subject to such IEA stock option, with any such cash payment to be paid and any such shares of MasTec common stock to be issued to each holder promptly after the effective time, but in any event no later than the fifth business day after the effective time. Any IEA stock option with an exercise price per share as of the effective time that is greater than or equal to $14.00 will be cancelled without any cash payment being made in respect thereof.

Restricted Stock Units

Each restricted stock unit that vests solely based on the passage of time with respect to shares of IEA common stock, whether vested or unvested, that is outstanding immediately prior to the effective time, will, at the effective time, be cancelled and converted into the right to receive (i) an amount in cash (without interest, and subject to deduction for any required withholding tax) equal to the product obtained by multiplying (x) the cash consideration and (y) the number of shares of IEA common stock subject to such restricted stock unit and (ii) a number of shares of MasTec common stock equal to the product obtained by multiplying (x) the stock consideration and (y) the number of shares of IEA common stock subject to such restricted stock unit, with any such cash payment to be paid and any such shares of MasTec common stock to be issued to each holder promptly after the effective time, but in any event no later than the fifth business day after the effective time.

Performance Stock Units

Each performance stock unit that vests in whole or in part based on the achievement of one or more performance goals with respect to shares of IEA common stock, whether vested or unvested, that is outstanding immediately prior to the effective time, will, at the effective time, be cancelled and converted into the right to receive (i) an amount in cash (without interest, and subject to deduction for any required withholding tax) equal to the product obtained by multiplying (x) the cash consideration and (y) the number of shares of IEA common stock subject to such performance stock unit assuming the target level of performance is achieved and (ii) a number of shares of MasTec common stock equal to the product obtained by multiplying (x) the stock consideration and (y) the number of shares of IEA common stock subject to such performance stock unit assuming the target level of performance is achieved, with any such cash payment to be paid and any such shares of MasTec common stock to be issued to each holder promptly after the effective time, but in any event no later than the fifth business day after the effective time.

Anti-Dilution Warrants

Each outstanding anti-dilution warrant will, immediately prior to the effective time, be cancelled and the registered holder thereof will be entitled to receive (i) an amount in cash, without interest, equal to the product obtained by multiplying (x) the cash consideration and (y) the number of shares of IEA common stock then issuable upon exercise of the anti-dilution warrant and (ii) a number of shares of MasTec common stock equal to

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product obtained by multiplying (x) the stock consideration and (y) the number of shares of IEA common stock then issuable upon exercise of the anti-dilution warrant, in each case as if the registered holder had exercised the anti-dilution warrant in full immediately prior to the effective time and acquired the applicable number of shares of IEA common stock then issuable thereunder as a result of such exercise.

Pre-Funded Warrants

Each pre-funded warrant that is outstanding as of immediately prior to the effective time will, at the effective time, be deemed exercised in full as a “cashless exercise” and the holder thereof will be entitled to receive (i) an amount in cash, without interest, equal to the product obtained by multiplying (x) the cash consideration and (y) the number of shares of IEA common stock then issuable upon exercise in full of the pre-funded warrant as a cashless exercise and (ii) a number of shares of MasTec common stock equal to product obtained by multiplying (x) the stock consideration and (y) the number of shares of IEA common stock then issuable upon exercise in full of the pre-funded warrant as a cashless exercise, in each case, calculated in accordance with and subject to the terms and conditions of the pre-funded warrant.

SPAC Warrants

Each outstanding SPAC warrant will, at the effective time, cease to represent a SPAC warrant in respect of shares of IEA common stock and will become a SPAC warrant exercisable for the merger consideration. If a holder properly exercises a SPAC warrant within 30 days following the public disclosure of the consummation of the merger pursuant to a current report on Form 8-K, the warrant price (as defined in the SPAC Warrant Agreement) with respect to such exercise will be reduced by an amount (in dollars) equal to the difference (but in no event less than zero) of (i) the warrant price in effect prior to such reduction minus (ii) (x) the per share consideration (as defined in the SPAC Warrant Agreement) minus (y) the Black-Scholes warrant value (as defined in the SPAC Warrant Agreement).

Series B Warrants

Each outstanding Series B warrant will, immediately prior to the effective time, be cancelled and the registered holder thereof will be entitled to receive (i) an amount in cash, without interest, equal to the product obtained by multiplying (x) the cash consideration and (y) the number of shares of IEA common stock then issuable upon exercise of the Series B warrant and (ii) a number of shares of MasTec common stock equal to product obtained by multiplying (x) the stock consideration and (y) the number of shares of IEA common stock then issuable upon exercise of the Series B warrant, in each case as if the registered holder had exercised the Series B warrant in full immediately prior to the effective time and acquired the applicable number of shares of IEA common stock then issuable thereunder as a result of such exercise.

Exchange and Payment Procedures in the Merger

Prior to the effective time, MasTec will enter into an agreement (in a form reasonably acceptable to the IEA) with IEA’s transfer agent to act as an exchange agent (referred to as the “exchange agent”) for the purpose of paying the merger consideration payable in respect of shares of IEA common stock converted into merger consideration pursuant to the merger agreement and the fractional share cash consideration. Prior to or as of the effective time, MasTec will deposit (or cause to be deposited) with the exchange agent (i) cash in an amount sufficient to make all payments of the cash consideration in respect of shares of IEA common stock pursuant to the merger agreement, (ii) the aggregate fractional share cash consideration payable in the merger to holders of shares of IEA common stock and (iii) evidence of MasTec common stock in book-entry form representing the number of shares of MasTec common stock sufficient to deliver the aggregate stock consideration payable in the merger to holders of shares of IEA common stock.

Promptly after the effective time and in any event not later than the third business day following the effective time, the surviving corporation will cause the exchange agent to mail to each holder of record of an

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outstanding certificate or outstanding certificates that immediately prior to the effective time represented outstanding shares of IEA common stock that were converted into the right to receive the merger consideration with respect thereto pursuant to the merger agreement, (i) a form of letter of transmittal (which will specify that delivery will be effected, and risk of loss and title to the certificates held by such person will pass, only upon proper delivery of the certificates to the exchange agent) and (ii) instructions for use in effecting the surrender of such certificates in exchange for the merger consideration payable with respect thereto pursuant to the merger agreement and the fractional share cash consideration payable pursuant to the merger agreement. Upon surrender of a certificate to the Exchange Agent, together with such letter of transmittal, duly completed and validly executed in accordance with the instructions thereto, the holder of such certificate will be entitled to receive in exchange therefor the merger consideration for each share of IEA common stock formerly represented by such certificate (subject to deduction for any required withholding tax), and the certificate so surrendered will forthwith be cancelled and the shares of MasTec common stock issued in connection with the foregoing will be in non-certificated book-entry form. Promptly after the effective time and in any event not later than the third business day following the effective time, the surviving corporation will cause the exchange agent to mail to each holder of record immediately prior to the effective time of uncertificated shares of IEA common stock represented by book entry customary instructions for use in effecting the surrender of book-entry shares in exchange for the merger consideration payable with respect thereto pursuant to the merger agreement and the fractional share cash consideration payable pursuant to the merger agreement. Upon receipt by the exchange agent of an “agent’s message” in customary form, and such other evidence of surrender, if any, as the exchange agent may reasonably request in respect of book-entry shares, the holder thereof will be entitled to receive in exchange therefore the merger consideration and the fractional share cash consideration payable pursuant to the merger agreement with respect to each share of IEA common stock formerly represented by such book-entry shares (subject to deduction for any required withholding tax) and the shares of MasTec common stock issued in connection with the foregoing will be in non-certificated book-entry form. No interest will be paid or accrued for the benefit of holders of certificates or book-entry shares on the merger consideration payable in respect of certificates or book-entry shares.

At any time following the date that is 12 months after the effective time, the surviving corporation will be entitled to require the exchange agent to deliver to it any funds (including any interest received with respect thereto) which have been made available to the exchange agent and which have not been disbursed to holders of certificates or book-entry shares, and thereafter such holders will be entitled to look to MasTec and the surviving corporation (subject to abandoned property, escheat or other similar laws) only as general creditors thereof with respect to the merger consideration (and any dividends or other distributions payable with respect thereto pursuant to the merger agreement and cash in lieu of any fractional shares payable with respect thereto pursuant to the merger agreement) payable upon due surrender of their certificate or book-entry shares.

Certain Representations and Warranties

The merger agreement contains customary representations and warranties made by MasTec, Merger Sub and IEA to each other. The representations and warranties in the merger agreement were made as of specific dates. The assertions embodied in those representations and warranties were made solely for purposes of the contract among MasTec, IEA and Merger Sub and may be subject to important qualifications and limitations agreed to by MasTec and IEA in connection with negotiating the terms of the merger agreement. Additionally, subject to certain exceptions, the representations and warranties made by MasTec, Merger Sub and IEA in the merger agreement are qualified by the information disclosed by MasTec or IEA, respectively, with the SEC at least two business days prior to the date of the merger agreement, excluding any risk factor disclosures, disclosure of risks in any “forward-looking statements” disclaimer and other statements that are similarly predictive or forward-looking in nature, in each case, other than any specific factual information contained therein. Moreover, certain representations and warranties may not be accurate or complete as of any specified date because they are subject to a contractual standard of materiality (including, in many cases, “material adverse effect”) different from those generally applicable to shareholders and in some cases may be qualified by disclosures made by one party to the other in disclosure letters delivered by such party to the other, which are not

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necessarily reflected in the merger agreement or were used for the purpose of allocating risk between MasTec and IEA rather than establishing matters as facts. Finally, information concerning the subject matter of the representations and warranties in the merger agreement may have changed since the date of the merger agreement, which may or may not be fully reflected in MasTec’s and IEA’s public disclosures. MasTec and IEA will provide additional disclosure in their public reports to the extent that they are aware of the existence of any material facts that are required to be disclosed under federal securities laws and that might otherwise contradict the terms and information contained in the merger agreement, and will update such disclosure as required by federal securities laws. The representations and warranties in the merger agreement do not survive the effective time. For the foregoing reasons, you should not rely on the representations and warranties in the merger agreement as statements of factual information. Some of the more significant representations and warranties that MasTec and IEA each made to the other relate to:

In addition, (i) IEA has made representations to MasTec relating to employee benefits, labor matters, environmental matters, taxes, existence and validity of, and compliance with, material contracts, customers and suppliers, insurance, interests in real and leased property, intellectual property, international trade law compliance, the inapplicability of state anti-takeover statutes, the opinion of its financial advisor, and surety bonds and (ii) MasTec has made representations to IEA regarding MasTec’s financial ability and its debt financing.

Definition of “Material Adverse Effect”

For purposes of the merger agreement, a “material adverse effect” with respect to a party and its subsidiaries is defined to mean any effect, change, circumstance, development, occurrence or event that, individually or in the aggregate, has had, or would reasonably be expected to have, a material adverse effect on the financial condition, business, assets, liabilities or results of operations of such party and its subsidiaries, taken as a whole. However, for purposes of determining whether there has been or there would or could be a material adverse effect with respect to a party and its subsidiaries, no event, change, circumstance, development, occurrence or effect directly

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or indirectly arising out of, attributable to or resulting from any of the following, alone or in combination, will be taken into account:

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Conduct of IEA’s Business Pending the Transaction

Prior to the effective time, except as expressly required by the merger agreement, as disclosed in the disclosure letter, as required by applicable law (including any public health measures) or as otherwise taken in good faith by IEA or any of its subsidiaries in response to COVID-19 or unless MasTec otherwise consents in writing (which consent will not be unreasonably withheld, conditioned or delayed), IEA agreed that it will, and will cause each of its subsidiaries to, conduct their respective business in the ordinary course of business in all material respects and use reasonable best efforts to preserve substantially intact their respective business organizations and material assets, to keep available the services of its and its subsidiaries’ current officers and key employees, to preserve their respective present relationships with material customers and material suppliers and comply in all material respects with all applicable laws.

Except as expressly required by the merger agreement, as disclosed in the disclosure letter, as required by applicable law (including any public health measures) or unless MasTec otherwise consents in writing (which consent will not be unreasonably withheld, conditioned or delayed), IEA will not, and IEA will cause each of its subsidiaries not to:

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Conduct of MasTec’s Businesses Pending the Transaction

Prior to the effective time, except as expressly required by the merger agreement, as required by applicable law (including any public health measures) or as otherwise taken in good faith by IEA or any of its subsidiaries

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in response to COVID-19 or unless IEA otherwise consents in writing (which consent will not be unreasonably withheld, conditioned or delayed), MasTec agreed that it will, and will cause each of its subsidiaries to, use reasonable best efforts to preserve substantially intact their respective business organizations and material assets, to keep available the services of its and its subsidiaries’ current officers and key employees, to preserve their respective present relationships with material customers and material suppliers and comply in all material respects with all applicable laws.

Except as expressly required by the merger agreement, as required by applicable law (including any public health measures), or unless IEA otherwise consents in writing (which consent will not be unreasonably withheld, conditioned or delayed), MasTec will not:

Prior to the earlier of the effective time and the termination of the merger agreement in accordance with its terms, and except as may otherwise be required by applicable law, required by the merger agreement or with the prior written consent of IEA (which consent will not be unreasonably withheld, conditioned or delayed), each of MasTec and Merger Sub agreed that it will not, directly or indirectly, make, or agree to make, any acquisition (whether by merger, consolidation or acquisition of stock or assets or otherwise) of any corporation, partnership or other business, organization or division thereof that would reasonably be expected to materially adversely affect or materially delay the ability of MasTec or Merger Sub to consummate the merger.

Restrictions on IEA’s Solicitation of Acquisition Proposals

On July 24, 2022, IEA agreed that it will immediately cease and cause to be terminated any existing activities, discussions or negotiations with any persons conducted heretofore with respect to any alternative acquisition proposal including, but not limited to, terminating the access to any existing electronic data rooms and ceasing to contact or communicate with other bidders.

In addition, IEA agreed, subject to the terms of the merger agreement, that neither it nor any of its subsidiaries will, and that it will cause its subsidiaries and IEA’s and its subsidiaries’ respective directors, officers, investment bankers, attorneys, accountants and other advisors or representatives not to, directly or indirectly:

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Notwithstanding the foregoing restrictions, at any time prior to obtaining the IEA stockholders’ approval of the transaction, IEA may, in response to an unsolicited bona fide written alternative acquisition proposal that did not result from a breach of the merger agreement and that the IEA board determines in good faith, after consultation with its financial advisors and outside legal counsel, constitutes or would reasonably be expected to lead to a superior proposal, (i) furnish information with respect to IEA and its subsidiaries to the person making such alternative acquisition proposal pursuant to a customary confidentiality agreement on terms substantially similar to those contained in the certain confidentiality agreement between IEA and MasTec (except for such changes specifically necessary in order for IEA to be able to comply with its obligations under the merger agreement and it being understood that IEA may enter into a confidentiality agreement without a standstill provision) and (ii) participate in discussions or negotiations with such person and its representatives regarding such alternative acquisition proposal; provided, that IEA will promptly provide or make available to MasTec any material non-public information concerning IEA or any of its subsidiaries that is provided to the person making such alternative acquisition proposal or its representatives which was not previously provided or made available to MasTec but in each case referred to in the foregoing clauses (i) and (ii), only if the IEA board determines in good faith, after consultation with its financial advisors and outside legal counsel, that the failure to take such action would reasonably be expected to be inconsistent with the directors’ fiduciary duties under applicable law.

IEA will promptly (and in any event within 24 hours) advise MasTec orally and in writing of (i) any alternative acquisition proposal, (ii) any request for non-public information relating to IEA or its subsidiaries, other than requests for information not related to, and not reasonably expected to lead to, an alternative acquisition proposal and (iii) any inquiry or request for discussion or negotiation, or any inquiry or request related to, or that would reasonably be expected to result in or lead to, an alternative acquisition proposal, including in each case the identity of the person making any such alternative acquisition proposal, inquiry or request and the material terms of any such alternative acquisition proposal, inquiry or request and copies of material communications received by IEA or any of its representatives from such person or its representatives related thereto and thereafter will keep MasTec informed, on a current basis, of the status and terms of any such proposals or offers and the status of any such discussions or negotiations, including any material amendments or proposed amendments as to price, proposed financing and other material terms thereof and provide MasTec with copies of all material communications received by IEA or any of its representatives from such person or its representatives related thereto.

An “alternative acquisition proposal” means any inquiry, proposal or offer from, or indication of interest in making a proposal or offer by, any person or group of persons other than MasTec or one of its subsidiaries relating to any transaction or series of related transactions (other than the transactions contemplated by the merger agreement), involving: (A) a merger, reorganization, consolidation, share exchange, business combination, recapitalization, liquidation, dissolution or similar transaction involving an acquisition of IEA (or any subsidiary or subsidiaries of IEA whose business (together with its subsidiaries’) constitutes 20% or more of the net revenues, net income or assets of IEA and its subsidiaries, taken as a whole); (B) the acquisition in any manner, directly or indirectly, of 20% or more of the equity securities or consolidated total assets of IEA and its subsidiaries, in each case other than the merger and the other transactions contemplated by the merger agreement; (C) the liquidation, dissolution (or the adoption of a plan of liquidation or dissolution), or recapitalization or other significant corporate reorganization of IEA or one or more of its subsidiaries which constitutes 20% or more of the net revenues, net income or assets of IEA and its subsidiaries, taken as a whole; or (D) any combination of the foregoing.

A “superior proposal” means any bona fide written alternative acquisition proposal on terms which the IEA board determines in good faith, after consultation with IEA’s outside legal counsel and financial advisors, to be (A) more favorable from a financial point of view to the holders of shares of IEA common stock than the merger

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and the other transactions contemplated by the merger agreement, taking into account all the terms and conditions of such proposal, and the merger agreement and (B) reasonably capable of being completed, in each case taking into account all financial, regulatory, legal and other aspects of such proposal, including the identity of the third party making such proposal, and any revisions to the terms of the merger agreement and the merger proposed by MasTec; provided, that for purposes of the definition of “superior proposal,” the references to “20%” in the definition of alternative acquisition proposal will be deemed to be references to “50%.”

IEA, including acting through the IEA board, will (A) take all action necessary to duly call, give notice of, convene and hold a meeting of its stockholders for the purpose of obtaining the IEA stockholders’ approval of the merger proposal and (B) subject to certain exceptions, include in the proxy statement the recommendation of the IEA board that the IEA stockholders vote in favor of the approval of the merger agreement. IEA will use reasonable best efforts to (i) solicit from the holders of shares of IEA common stock proxies in favor of the adoption of the merger agreement and approval of the merger and (ii) take all other actions necessary or advisable to secure the vote or consent of the holders of shares of IEA common stock required by applicable law to obtain such approval. However, the IEA board may change its recommendation. See “The Agreements – Transaction Structure – Change of Recommendation of the IEA Board” on page 92 below.

Change of Recommendation by the IEA Board