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                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549




                                    FORM 11-K




                 ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE
                        SECURITIES EXCHANGE ACT OF 1934
                  For the fiscal year ended December 31, 1998



                        Commission File Number 001-08106







                                THE MASTEC, INC.
                         401(K) RETIREMENT SAVINGS PLAN
 (Full title of the plan and the address of the plan. if different from that of
                             the isuer named below:)





















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Table of Contents Pages ----- Report of Independent Accountants ......................................... 2 Financial Statements: Statement of Net Assets Available for Benefits ....................... 3 as of December 31, 1998 Statement of Net Assets Available for Benefits as of December 31, 1997 .......................................... 4 Statement of Changes in Net Assets Available for Benefits for the year ended December 31, 1998 ............................. 5 Statement of Changes in Net Assets Available for Benefits for the year ended December 31, 1997 ............................. 6 Notes to Financial Statements ........................................ 7 Supplemental Schedules: Item 27a of Form 5500 - Schedule of Assets Held for Investment Purposes as of December 31, 1998 ................................. 14 Item 27d of Form 5500 - Schedule of Reportable Transactions for the year ended December 31, 1998 ............................. 15 Signatures ................................................................ 16 Consent of Independent Accountants ........................................ 17 1

Report of Independent Accountants To the Board of Trustees of the MasTec, Inc. 401(k) Retirement Savings Plan: In our opinion, the accompanying statements of net assets available for benefits and the related statements of changes in net assets available for benefits present fairly, in all material respects, the net assets available for benefits of The MasTec, Inc. 401(k) Retirement Savings Plan (the "Plan") at December 31, 1998 and 1997, and the changes in net assets available for benefits for the years ended December 31, 1998 and 1997 in conformity with generally accepted accounting principles. These financial statements are the responsibility of the Plan's management; our responsibility is to express an opinion on these financial statements based on our audits. We conducted our audits of these statements in accordance with generally accepted auditing standards which require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement. An audit includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, assessing the accounting principles used and significant estimates made by management, and evaluating the overall financial statement presentation. We believe that our audits provide a reasonable basis for the opinion expressed above. Our audits were conducted for the purpose of forming an opinion on the basic financial statements taken as a whole. The supplemental schedules of Assets Held for Investment Purposes as of December 31, 1998, and Reportable Transactions for the year then ended, are presented for the purpose of additional analysis and are not a required part of the basic financial statements but are supplementary information required by the Department of Labor's Rules and Regulations for Reporting and Disclosure under the Employee Retirement Income Security Act of 1974. The fund information in the statements of net assets available for benefits and the statement of changes in net assets available for benefits is presented for purposes of additional analysis rather than to present the net assets available for plan benefits and changes in net assets available for benefits of each fund. These supplemental schedules and fund information are the responsibility of the Plan's management. The supplemental schedules and fund information have been subjected to the auditing procedures applied in the audits of the basic financial statements and, in our opinion, are fairly stated in all material respects in relation to the basic financial statements taken as a whole. June 18, 1999 2

THE MASTEC, INC. 401(K) RETIREMENT SAVINGS PLAN STATEMENT OF NET ASSETS AVAILABLE FOR BENEFITS as of December 31, 1998 MasTec Life Guaranteed Aggressive Growth & Common Insurance Certificate Growth Bond Growth Income Stock Fund Fund Fund Funds Funds Funds Funds ----------- ----------- ----------- ----------- ----------- ----------- ----------- Assets: Investments at fair value .... $ 1,979,090 $ 48,349 $ 138,619 $ 3,338,136 $ 954,401 $ 2,301,387 $ 2,399,920 Participant notes receivable . 0 0 7,197 107,305 25,782 123,867 91,844 ----------- ----------- ----------- ----------- ----------- ----------- ----------- Total investments ... 1,979,090 48,349 145,816 3,445,441 980,183 2,425,254 2,491,764 ----------- ----------- ----------- ----------- ----------- ----------- ----------- Receivables: Participants' contributions 26,198 0 6,097 107,020 43,499 44,713 77,174 Employer's contributions .. 65,278 0 0 0 0 0 0 ----------- ----------- ----------- ----------- ----------- ----------- ----------- Total receivables ... 91,476 0 6,097 107,020 43,499 44,713 77,174 ----------- ----------- ----------- ----------- ----------- ----------- ----------- Net assets available for benefits ................... $ 2,070,566 $ 48,349 $ 151,913 $ 3,552,461 $ 1,023,682 $ 2,469,967 $ 2,568,938 =========== =========== =========== =========== =========== =========== =========== THE MASTEC, INC. 401(K) RETIREMENT SAVINGS PLAN STATEMENT OF NET ASSETS AVAILABLE FOR BENEFITS as of December 31, 1998 (CONTINUED) International Short Term Funds Fund Other Total ----------- ----------- ----------- ----------- Assets: Investments at fair value .... $ 468,155 $ 6,186,843 $ 116,985 $17,931,885 Participant notes receivable . 10,353 219,282 0 585,630 ----------- ----------- ----------- ----------- Total investments ... 478,508 6,406,125 116,985 18,517,515 ----------- ----------- ----------- ----------- Receivables: Participants' contributions 18,115 47,061 0 369,877 Employer's contributions .. 0 0 0 65,278 ----------- ----------- ----------- ----------- Total receivables ... 18,115 47,061 0 435,155 ----------- ----------- ----------- ----------- Net assets available for benefits ................... $ 496,623 $ 6,453,186 $ 116,985 $18,952,670 =========== =========== =========== =========== The accompanying notes are an integral part of these financial statements. 3

THE MASTEC, INC. 401(K) RETIREMENT SAVINGS PLAN STATEMENT OF NET ASSETS AVAILABLE FOR BENEFITS as of December 31, 1997 MasTec Life Guaranteed Aggressive Growth & Common Insurance Certificate Growth Bond Growth Income Stock Fund Fund Fund Funds Funds Funds Funds ----------- ----------- ----------- ----------- ----------- ----------- ----------- Assets: Investments at fair value $ 1,306,381 $ 54,920 $ 51,492 $ 1,146,047 $ 206,786 $ 1,489,409 $ 1,217,563 Participant notes receivable 3,000 0 740 44,800 4,374 78,438 53,555 ----------- ----------- ----------- ----------- ----------- ----------- ----------- Total investments 1,309,381 54,920 52,232 1,190,847 211,160 1,567,847 1,271,118 ----------- ----------- ----------- ----------- ----------- ----------- ----------- Receivables: Participants' contributions 21,736 0 2,079 44,498 9,271 20,005 29,583 Employer's contributions 59,635 0 0 0 0 0 0 ----------- ----------- ----------- ----------- ----------- ----------- ----------- Total receivables 81,371 0 2,079 44,498 9,271 20,005 29,583 ----------- ----------- ----------- ----------- ----------- ----------- ----------- Net assets available for benefits $ 1,390,752 $ 54,920 $ 54,311 $ 1,235,345 $ 220,431 $ 1,587,852 $ 1,300,701 =========== =========== =========== =========== =========== =========== =========== THE MASTEC, INC. 401(K) RETIREMENT SAVINGS PLAN STATEMENT OF NET ASSETS AVAILABLE FOR BENEFITS as of December 31, 1997 (CONTINUED) International Short Term Funds Fund Total ----------- ----------- ----------- Assets: Investments at fair value $ 115,545 $ 2,048,355 $ 7,636,498 Participant notes receivable 669 195,951 381,527 ----------- ----------- ----------- Total investments 116,214 2,244,306 8,018,025 ----------- ----------- ----------- Receivables: Participants' contributions 5,421 25,831 158,424 Employer's contributions 0 0 59,635 ----------- ----------- ----------- Total receivables 5,421 25,831 218,059 ----------- ----------- ----------- Net assets available for benefits $ 121,635 $ 2,270,137 $ 8,236,084 =========== =========== =========== The accompanying notes are an integral part of these financial statements. 4

THE MASTEC, INC. 401(K) RETIREMENT SAVINGS PLAN STATEMENT OF CHANGES IN NET ASSETS AVAILABLE FOR BENEFITS for the year ended December 31, 1998 MasTec Life Guaranteed Aggressive Common Insurance Certificate Growth Bond Growth Stock Fund Fund Fund Funds Funds Funds ----------- ----------- ----------- ----------- ----------- ----------- Additions to net assets attributed to: Investment income: Net (depreciation) appreciation in fair value of investments $ (162,287) $ 0 $ 0 $ 426,344 $ 59,190 $ 392,578 Interest 0 2,197 4,955 0 0 0 ----------- ----------- ----------- ----------- ----------- ----------- (162,287) 2,197 4,955 426,344 59,190 392,578 Contributions: Participants' 314,331 0 161,039 2,075,457 679,598 662,236 Employer's 502,814 0 0 0 0 0 ----------- ----------- ----------- ----------- ----------- ----------- Total additions 654,858 2,197 165,994 2,501,801 738,788 1,054,814 ----------- ----------- ----------- ----------- ----------- ----------- Deductions from net assets attributed to: Participants' withdrawals 153,433 8,768 72,077 168,079 90,019 162,138 ----------- ----------- ----------- ----------- ----------- ----------- Total deductions 153,433 8,768 72,077 168,079 90,019 162,138 ----------- ----------- ----------- ----------- ----------- ----------- Net (decrease) increase prior to transfers 501,425 (6,571) 93,917 2,333,722 648,769 892,676 Transfers 178,389 0 3,685 (16,606) 154,482 (10,561) ----------- ----------- ----------- ----------- ----------- ----------- Net increase (decrease) 679,814 (6,571) 97,602 2,317,116 803,251 882,115 Net assets available for benefits: Beginning of year 1,390,752 54,920 54,311 1,235,345 220,431 1,587,852 ----------- ----------- ----------- ----------- ----------- ----------- End of year $ 2,070,566 $ 48,349 $ 151,913 $ 3,552,461 $ 1,023,682 $ 2,469,967 =========== =========== =========== =========== =========== =========== THE MASTEC, INC. 401(K) RETIREMENT SAVINGS PLAN STATEMENT OF CHANGES IN NET ASSETS AVAILABLE FOR BENEFITS for the year ended December 31, 1998 (CONTINUED) Growth & Income International Short Term Funds Funds Fund Other Total ----------- ----------- ----------- ----------- ----------- Additions to net assets attributed to: Investment income: Net (depreciation) appreciation in fair value of investments $ 254,808 $ 53,384 $ 160,210 $ 0 $ 1,184,227 Interest 0 0 0 0 7,152 ----------- ----------- ----------- ----------- ----------- 254,808 53,384 160,210 0 1,191,379 Contributions: Participants' 1,158,014 331,440 5,180,466 116,985 10,679,566 Employer's 0 0 0 0 502,814 ----------- ----------- ----------- ----------- ----------- Total additions 1,412,822 384,824 5,340,676 116,985 12,373,759 ----------- ----------- ----------- ----------- ----------- Deductions from net assets attributed to: Participants' withdrawals 136,098 32,304 834,257 0 1,657,173 ----------- ----------- ----------- ----------- ----------- Total deductions 136,098 32,304 834,257 0 1,657,173 ----------- ----------- ----------- ----------- ----------- Net (decrease) increase prior to transfers 1,276,724 352,520 4,506,419 116,985 10,716,586 Transfers (8,487) 22,468 (323,370) 0 0 ------------ ----------- ----------- ----------- ----------- Net increase (decrease) 1,268,237 374,988 4,183,049 116,985 10,716,586 Net assets available for benefits: Beginning of year 1,300,701 121,635 2,270,137 0 8,236,084 ----------- ----------- ----------- ----------- ----------- End of year $ 2,568,938 $ 496,623 $ 6,453,186 $ 116,985 $18,952,670 =========== =========== =========== =========== =========== The accompanying notes are an integral part of these financial statements. 5

THE MASTEC, INC. 401(K) RETIREMENT SAVINGS PLAN STATEMENT OF CHANGES IN NET ASSETS AVAILABLE FOR BENEFITS for the year ended December 31, 1997 MasTec Life Guaranteed Aggressive Common Insurance Certificate Growth Bond Growth Stock Fund Fund Fund Funds Funds Funds ----------- ----------- ----------- ----------- ----------- ----------- Additions to net assets attributed to: Investment income: Net (depreciation) appreciation in fair value of investments $ (584,591) $ 0 $ 0 $ 116,102 $ 15,728 $ 317,457 Interest 0 2,715 1,624 0 0 0 ----------- ----------- ----------- ----------- ----------- ----------- (584,591) 2,715 1,624 116,102 15,728 317,457 Contributions: Participants' 342,267 0 28,023 647,122 133,614 307,471 Employer's 376,036 0 0 0 0 0 ----------- ----------- ----------- ----------- ----------- ----------- Total additions 133,712 2,715 29,647 763,224 149,342 624,928 ----------- ----------- ----------- ----------- ----------- ----------- Deductions from net assets attributed to: Participants' withdrawals 160,941 15,667 2,927 88,862 47,051 618,046 ----------- ----------- ----------- ----------- ----------- ----------- Total deductions 160,941 15,667 2,927 88,862 47,051 618,046 ----------- ----------- ----------- ----------- ----------- ----------- Net (decrease) increase prior to transfers (27,229) (12,952) 26,720 674,362 102,291 6,882 Transfers 179,680 0 7,077 (51,055) (14,023) (32,645) ----------- ----------- ----------- ----------- ----------- ----------- Net increase (decrease) 152,451 (12,952) 33,797 623,307 88,268 (25,763) Net assets available for benefits: Beginning of year 1,238,301 67,872 20,514 612,038 132,163 1,613,615 =========== =========== =========== =========== =========== =========== End of year $ 1,390,752 $ 54,920 $ 54,311 $ 1,235,345 $ 220,431 $ 1,587,852 =========== =========== =========== =========== =========== =========== THE MASTEC, INC. 401(K) RETIREMENT SAVINGS PLAN STATEMENT OF CHANGES IN NET ASSETS AVAILABLE FOR BENEFITS for the year ended December 31, 1997 (CONTINUED) Growth & Income International Short Term Funds Funds Fund Total ----------- ----------- ----------- ----------- Additions to net assets attributed to: Investment income: Net (depreciation) appreciation in fair value of investments $ 172,380 $ 6,255 $ 95,419 $ 138,750 Interest 0 0 0 4,339 ----------- ----------- ----------- ----------- 172,380 6,255 95,419 143,089 Contributions: Participants' 469,240 88,870 438,026 2,454,633 Employer's 0 0 0 376,036 ----------- ----------- ----------- ----------- Total additions 641,620 95,125 533,445 2,973,758 ----------- ----------- ----------- ----------- Deductions from net assets attributed to: Participants' withdrawals 204,846 32,120 938,652 2,109,112 ----------- ----------- ----------- ----------- Total deductions 204,846 32,120 938,652 2,109,112 ----------- ----------- ----------- ----------- Net (decrease) increase prior to transfers 436,774 63,005 (405,207) 864,646 Transfers 49,141 (23,987) (114,188) 0 ----------- ----------- ----------- ----------- Net increase (decrease) 485,915 39,018 (519, 395) 864,646 Net assets available for benefits: Beginning of year 814,786 82,617 2,789,532 7,371,438 =========== =========== =========== =========== End of year $ 1,300,701 $ 121,635 $ 2,270,137 $ 8,236,084 =========== =========== =========== =========== The accompanying notes are an integral part of these financial statements. 6

THE MASTEC, INC. 401(K) RETIREMENT SAVINGS PLAN NOTES TO FINANCIAL STATEMENTS 1. Description of Plan: The following description of The MasTec, Inc. (the "Company" or "MasTec") 401(k) Retirement Savings Plan (the "Plan") provides only general information. The Plan agreement contains a more complete description of the Plan's provisions. General The Plan is a defined contribution plan covering all employees of the Company who are age twenty-one or older and have one year of service. Eligible participants may enter the Plan on January 1 or July 1. It is subject to the provisions of the Employee Retirement Income Security Act of 1974 ("ERISA") and is exempt from federal and state income taxes. The Plan is administered by the Employee Benefits Committee (Plan Administrators). Great-West Life & Annuity Insurance Company is the Trustee and Recordkeeper of the Plan for all funds except for the MasTec Common Stock Fund which the Trustee is Norwest Bank, Minnesota, N.A. Plan assets are held by the Trustee. At December 31, 1998, Benefit Services Corporation was the Trustee and Recordkeeper of certain Plan assets of a company acquired by MasTec, Inc. in 1998. Subsequent to December 31, 1998, these assets were transferred to Great-West Life & Annuity Insurance Company and invested in the Plan upon the employee's elections. Contributions Participants may contribute from 1% to 15% of their pre-tax annual compensation, subject to certain dollar amount limits, as defined in the plan agreement. The maximum contribution allowed during 1998 and 1997 was $10,000 and $9,500, respectively. The Company's contributions are discretionary. During 1998, the Company's contributions were 25% of each dollar up to 4% of the participant's gross salary. The Company match is exclusively in MasTec Common Stock. During 1998, the 401(k) plans of certain companies acquired by MasTec, Inc. were converted to the Plan, with the related employer becoming participants. All of the assets of these plans were converted at a fair value of approximately $6,653,000 and invested in the Plan upon the employee's elections. Such amounts are included as participants' contributions for 1998. 7

THE MASTEC, INC. 401(K) RETIREMENT SAVINGS PLAN NOTES TO FINANCIAL STATEMENTS, Continued 1. Description of the Plan, Continued: Participant Accounts Each participant's account is credited with the participant's contribution, the Company's contribution, if any, rollovers into the Plan and an allocation of the participant accounts earnings. Each participant's account is reduced by any withdrawals or distributions and an allocation of (a) his share of investment losses and depreciation in value of investments and (b) any administrative fees paid by the Plan. The benefit to which a participant is entitled is the participant's vested account balance. Investment Options Upon enrollment in the Plan, a participant may direct contributions to any of the following investment options. Participants may elect to invest contributions in a single fund in 1% increments, among any of the following: MasTec Common Stock Fund - Funds are invested solely in shares of the common stock, par value $0.10 per share of MasTec, Inc. The fund will buy up to 500,000 shares, as determined under the rules of ERISA and the Internal Revenue Code (IRC). A participant may not invest more than 50% of his aggregate contributions in the MasTec, Inc. common stock fund. Life Insurance Fund - The fund was not offered as an investment option to participants after July 1, 1994. Guaranteed Certificate Fund - Funds are invested in certificates of deposit guaranteed by Great-West Life & Annuity Insurance Company. Aggressive Growth Funds - Funds are invested in: American Century - Twentieth Century Ultra Investors Fund, managed by American Century Investment Management, Inc.; AIM Constellation Fund, managed by AIM Advisors, Inc.; Maxim Small-Cap Index Portfolio, managed by GW Capital Management, Inc., seeks to mirror the Russell 2000 Index; Maxim Growth Index Portfolio, managed by GW Capital Management, Inc., seeks to mirror the Russell 1000 Growth Index; Maxim Small-Cap Aggressive Growth Portfolio, managed by Loomis Sayles & Company, seeks to mirror the performance of the Loomis Sayles Small-Cap Fund; and Lord Abbett Developing Growth Fund, managed by Lord Abbett & Co. 8

1. Description of the Plan, Continued: Investment Options, Continued Bond Funds - Funds are invested in: Maxim U.S. Government Mortgage Securities Portfolio, managed by GW Capital Management, Inc.; Maxim Investment Grade Corporate Bond Portfolio, managed by GW Capital Management, Inc.; Maxim Corporate Bond Portfolio, managed by Loomis Sayles & Company, seeks to mirror the performance of Loomis Sayles Bond Fund; Putnam Global Governmental Income Fund, managed by Putnam Investment Management, Inc.; and Maxim Short-Term Maturity Bond Portfolio, managed by GW Capital Management, Inc. Growth Funds - Funds are invested in: Fidelity Advisor Growth Opportunities Fund, managed by Fidelity Management and Research Company; Orchard Index 500, managed by GW Capital Management, Inc., seeks to mirror Standard & Poor's 500 Index; AIM Weingarten Fund, managed by AIM Advisors, Inc.; Maxim Small-Cap Value Portfolio, managed by Ariel Capital Management; and Maxim Mid-Cap Growth Portfolio, managed by T. Rowe Price, seeks to mirror T. Rowe Price Mid-Cap Growth Fund. Growth & Income Funds - Funds are invested in: Maxim Blue Chip Portfolio, managed by the Founders Funds; AIM Charter Fund, managed by AIM Advisors, Inc.; Maxim Value Index Portfolio, managed by GW Capital Management, Inc., seeks to mirror the Russell 1000 Value Index; Putnam Fund for Growth & Income, managed by Putnam Investment Management, Inc.; and Fidelity Advisor Equity Income Fund, managed by Fidelity Management and Research Company. 9

1. Description of the Plan, Continued: Investment Options, Continued International Funds - Funds are invested in: Putnam Global Growth Fund, managed by Putnam Investment Management, Inc.; Maxim Foreign Equity Portfolio, managed by Loomis Sayles & Company, seeks to mirror the performance of the New England International Equity Fund; Fidelity Advisor Overseas Fund, managed by Fidelity Management and Research Company; Orchard Index Pacific Fund, managed by GW Capital Management, Inc.; and Orchard Index European Fund, managed by GW Capital Management, Inc. Short-Term Fund - Funds are invested in: Maxim Money Market Portfolio, managed by GW Capital Management, Inc. Other - Funds included in other, represent assets of a 401(k) plan of a certain company acquired by MasTec, Inc. during 1998. Funds are invested in: Fidelity Advisor Growth Opportunity Fund, managed by Fidelity Management and Research Company. Fidelity Equity Income Fund, managed by Fidelity Management and Research Company. Fidelity Advisor Government Investment Fund, managed by Fidelity Management and Research Company. Fidelity Advisor Overseas Fund, managed by Fidelity Management and Research Company. Transfers and Rollovers Participants may rollover balances held in other qualified retirement plans at the discretion of the Plan Administrators. Withdrawals Certain withdrawals from participant accounts are only allowed for financial hardship (in accordance with IRS regulations). Participant Notes Receivable Participants may borrow a maximum of the lesser of (1) $50,000 or (2) fifty percent (50%) of their individual vested account balance. Loan terms range from 1-5 years or up to 20 years for the purchase of a primary residence. The loans bear interest at the published prime rate in the Wall Street Journal plus 1%. 10

1. Description of the Plan, Continued: Payment of Benefits On termination of service, due to death, disability, or retirement, a participant receives payment of the vested accrued benefit in a single lump sum or the payment can be deferred under certain circumstances to normal retirement age. For termination of service due to other reasons, a participant is entitled to receive only the vested percentage of his account balance. Vesting Participants are immediately vested in their contributions and rollovers and the earnings thereon. Participants are vested in Company contributions, if any, to the extent reflected below: Years of Service Percentage ---------------- ---------- 1 0% 2 20% 3 40% 4 60% 5 80% 6 or more 100% Participants forfeit the portion of their account balance to the extent not vested. 2. Summary of Significant Accounting Policies: The significant accounting policies followed by the Plan are as follows: Basis of Accounting The financial statements of the Plan are prepared in conformity with generally accepted accounting principles. Use of Estimates The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of additions and deductions during the reporting period. Actual results could differ from those estimates. 11

2. Summary of Significant Accounting Policies, Continued: Risk and Uncertainties The plan provides for various investment options in any combination of stocks, bonds, fixed income securities, mutual funds, and other investment securities. Investment securities are exposed to various risks, such as interest rate, market and credit. Due to the level of risk associated with certain investment securities and the level of uncertainty related to changes in the value of investment securities, it is at least reasonably possible that changes in risks in the near term would materially affect participants' account balances and the amounts reported in the statement of net assets available for plan benefits and the statement of changes in net assets available for plan benefits. Valuation of Investments and Income Recognition The Plan's investments are valued by the trustees (Note 1) and are stated at fair value using quoted market prices. Purchase and sales transactions are recorded on a trade date basis. Any gain or loss resulting from the sale of fund units is determined as the difference between the sales proceeds and the average cost of the units sold. Investment income is recorded on the accrual basis. Investment Income The Plan presents in the statement of changes in net assets available for benefits the net appreciation/depreciation in the fair value of its investments which consists of the realized gains or losses and the unrealized appreciation (depreciation) on those investments. Participant Withdrawals Withdrawals made by participants are recorded when paid. Administrative Costs All administrative expenses of the Plan, including, without limitation, the allocable portion of compensation of plan administrative staff and fees of employee benefits consultants, legal counsel, and auditors' fees are chargeable to the Plan. The Company may, at its sole discretion, pay any such expenses, in whole or in part. The Company assumed responsibility for administrative expenses for the years ended December 31, 1998 and 1997. 12

3. Plan Termination: Although it has not expressed any intent to do so, the Company has the right under the Plan to discontinue its contributions at any time and to terminate the Plan subject to the provisions of ERISA. In the event of Plan termination, participants will become 100% vested in their accounts. 4. Tax Status: The Internal Revenue Service has determined and informed the Company by a letter dated June 17, 1997, that the Plan is designed in accordance with applicable sections of the IRC. The Plan has been amended since receiving the determination letter. However, the Plan Administrator and the Plan's legal counsel believe that the Plan is designed and is currently being operated in compliance with the applicable requirements of the IRC. 13

THE MASTEC, INC. 401(K) RETIREMENT SAVINGS PLAN ITEM 27a OF FORM 5500 - SCHEDULE OF ASSETS HELD FOR INVESTMENT PURPOSES as of December 31, 1998 Participating (a) Units or Par Value (b) Identity of Party (c) Description of Investment (d) Cost (e)Fair Value ------------------ ----------------- ------------------------- ---------- ------------- 3,287 Maxim Blue Chip Portfolio Growth & Income Fund $ 61,804 $ 68,963 4,472 AIM Charter Fund Growth & Income Fund 100,008 124,772 9,297 Maxim Value Index Portfolio Growth & Income Fund 197,054 223,809 18,177 Putnam Fund for Growth & Income Growth & Income Fund 350,535 401,402 41,183 Fidelity Advisor Equity Income Fund Growth & Income Fund 534,730 740,609 3,364 Maxim U.S. Government Mortgage Securities Portfolio Bond Fund 51,788 53,488 1,618 Maxim Investment Grade Corporate Bond Portfolio Bond Fund 48,287 49,929 4,806 Maxim Corporate Bond Portfolio Bond Fund 72,722 74,442 4,364 Putnam Global Governmental Income Fund Bond Fund 49,261 51,246 3,454 Maxim Short-Term Maturity Bond Portfolio Bond Fund 40,011 40,955 315,965 Maxim Money Market Portfolio Short-Term Fund 5,943,774 6,186,843 69,361 Fidelity Advisor Growth Opportunities Fund Growth Fund 1,056,887 1,638,762 3,312 Orchard Index 500 Growth Fund 198,094 248,644 8,662 AIM Weingarten Fund Growth Fund 199,157 248,599 1,223 Maxim Small-Cap Value Portfolio Growth Fund 20,384 22,365 10,675 Maxim Mid-Cap Growth Portfolio Growth Fund 126,311 143,017 N/A Great-West Life & Annuity Insurance Company Guaranteed Certificate Fund 138,619 138,619 26,429 American Century - Twentieth Century Ultra Fund Aggressive Growth Fund 731,544 892,197 15,731 AIM Constellation Fund Aggressive Growth Fund 421,925 489,557 4,110 Maxim Small-Cap Index Portfolio Aggressive Growth Fund 64,519 66,514 11,742 Maxim Growth Index Portfolio Aggressive Growth Fund 281,053 340,048 9,023 Maxim Small-Cap Aggressive Growth Portfolio Aggressive Growth Fund 157,763 165,794 244 The Lord Abbett Developing Growth Fund Aggressive Growth Fund 2,083 2,421 17,221 Putnam Global Growth Fund International Fund 295,674 343,008 1,496 Maxim Foreign Equity Portfolio International Fund 18,209 18,564 4,697 Fidelity Advisor Overseas Fund International Fund 61,129 63,881 1,729 Orchard Index Pacific Fund International Fund 11,522 12,426 2,250 Orchard Index European Fund International Fund 27,758 30,276 64,863 Profile Series I Aggressive Growth Fund 1,180,973 1,381,605 43,047 Profile Series II Growth and Income Fund 735,512 840,365 25,607 Profile Series III Bond Fund 416,516 457,555 9,806 Profile Series IV Bond Fund 146,594 158,112 4,627 Profile Series V Bond Fund 65,877 68,674 90,319 MasTec, Inc. Common Stock Fund 2,154,020 1,979,090 N/A First Colony Life Insurance Company Life Insurance Fund 111,998 48,349 N/A Participant loans, fully amortized Loans to participants 8% - 11% 0 585,630 N/A Other Various Mutual Funds 116,985 116,985 ---------- ----------- $16,191,080 $18,517,515 =========== =========== 14

THE MASTEC, INC. 401(K) RETIREMENT SAVINGS PLAN ITEM 27d OF FORM 5500 - SCHEDULE OF REPORTABLE TRANSACTIONS * for the year ended December 31, 1998 (f) Value of Assets (c) Purchase (d) Selling (e) Cost of on Transaction (g) Net Gain (a) Identity of Party Involved (b) Description of Assets Price Price Asset Date or (Loss) --------------------------- ------------------------- ---------- ---------- ---------- ----------- ----------- MasTec, Inc. MasTec Common Stock Fund Purchases $ 986,179 $ 0 $ 0 $ 986,179 $ 0 Sales 0 232,723 227,283 0 5,440 Great -West Life & Annuity Aggressive Growth Funds Insurance Company Purchases 2,362,731 0 0 2,362,731 0 Sales 0 596,835 562,208 0 34,627 Great -West Life & Annuity Growth Funds Insurance Company Purchases 813,260 0 0 813,260 0 Sales 0 393,893 319,862 0 74,031 Great -West Life & Annuity Growth and Income Funds Insurance Company Purchases 1,325,861 0 0 1,325,861 0 Sales 0 397,424 373,550 0 23,874 Great -West Life & Annuity Short Term Fund Insurance Company Purchases 5,511,942 0 0 5,511,942 0 Sales 0 1,590,101 1,553,510 0 36,591 Great-West Life & Annuity Bond Funds Insurance Company Purchases 920,249 0 0 920,249 0 Sales 0 231,825 223,480 0 8,345 Great-West Life & Annuity International Funds Insurance Company Purchases 383,819 0 0 383,817 0 Sales 0 84,597 80,816 0 3,781 * Under ERISA, a reportable transaction is defined as a transaction or series of transactions during the plan year that involves more than 5% of the fair value of the plan assets at the beginning of the plan year. 15

SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the Trustees (or other persons who administer the employee benefit plan) have duly caused this annual report to be signed on its behalf by the undersigned hereunto duly authorized. THE MASTEC, INC. 401(K) RETIREMENT SAVINGS PLAN Date: June 30, 1999 /s/ CARMEN M. SABATER --------------------- Carmen M. Sabater Senior Vice President - Director of Finance (Trustee) Date: June 30, 1999 /s/ JOSE SARIEGO --------------------- JOSE SARIEGO Senior Vice President - General Counsel (Trustee) 16

Consent of Independent Accountants We hereby consent to the incorporation by reference in the Registration Statement on Form S-8 (File No. 33-55327) of MasTec, Inc. of our report dated June 18, 1999 relating to the financial statements, which appear in this Annual Report of The MasTec, Inc. 401(k) Retirement Savings Plan on Form 11-K for the year ended December 31, 1998. Miami, Florida June 30, 1999 17