Share ownership by each of the persons reporting on this Schedule 13D reflect transfers among certain of the reporting persons as well as grants of equity compensation to Mr. Mas since January 13, 2023, all as previously reported on Forms 4 filed by Mr. Mas.

The purpose of this filing to is report the entry by JM Holdings I on August 18, 2025 into an amendment (the "Third Amendment") to the previously reported prepaid variable forward sale contract entered into by JM Holdings I with an unaffiliated party (the "2019 Prepaid Forward Contract," and, as amended to date, the "Prepaid Forward Contract"). The Third Amendment amends the Floor Price (as defined below) and Cap Price (as defined below) for each Tranche 2 Component (as defined below), which were determined based on the volume weighted average price (the "VWAP") of MasTec, Inc.'s common stock for a specified period ended on August 21, 2025, and appropriately adjusts the number of Shares to be delivered on the respective valuation date for each Tranche 2 Component, with such adjustment resulting in a reduction in the number of Shares pledged under the Prepaid Forward Contract to 1,099,335 Shares. The Prepaid Forward Contract provides for the settlement of the transaction, at the option of JM Holdings I, in cash or in Shares. At settlement JM Holdings I will be obligated to deliver to the buyer, on the applicable date in August or September 2026 or 2027 for the applicable component (each, a "Valuation Date") in the first ("Tranche 1") or second ("Tranche 2") tranche, as applicable, of 15 components each ("Tranche 1 Components" or "Tranche 2 Components"), at JM Holdings I's option, up to 100% of the number of Shares pledged for such component or an equivalent amount of cash. JM Holdings I entered into the 2019 Prepaid Forward Contract to provide funds for investment in the Miami Major League Soccer franchise. For more information on the terms of the Prepaid Forward Contract, please see Item 6 below.

By Jorge Mas: 11,872,231, 15.0%. The Shares beneficially owned by Jorge Mas include: 5,665,484 Shares owned by JM Holdings I, which is controlled by JM Holdings, of which Jorge Mas is the sole member; 848,941 Shares owned by the JM Trust, one of the trustees of which is Jorge Mas's spouse; 425,000 Shares owned by the JR Trust of which Jorge Mas is a trustee; 276,000 Shares owned by Mas Partners III, in which Mas Partners is a member and of which Jorge Mas is the sole member; 100,000 Shares owned by the Family Foundation, a Florida not-for-profit corporation, of which Jorge Mas is the president and a member of the Board of Directors; and 4,556,806 Shares owned individually by Jorge Mas. Jorge Mas disclaims beneficial ownership of all Shares held by the JR Trust, the JM Trust, Mas Partners III and the Family Foundation, except, in each case, to the extent of his pecuniary interest therein, if any. 1,099,335 Shares of Common Stock owned by JM Holdings I are subject to the Prepaid Forward Contract and are pledged as collateral to secure JM Holdings I's obligations under such Prepaid Forward Contract. By JM Holdings I: 5,665,484, 7.2% By JM Holdings: 5,665,484, 7.2% By JM Trust: 848,941, 1.1% By JR Trust: 425,000, 0.5% By Mas Partners III: 276,000, 0.3% By Mas Partners: 276,000, 0.3% By Family Foundation: 100,000, 0.1% The percentage of beneficial ownership is based upon 78,907,954 Shares of Common Stock outstanding as of July 28, 2025.

The Reporting Person's responses to cover page Items 7 through 10 of this 13D/A are hereby incorporated by reference in this Item 5.

The Reporting Person's responses to Items 4(a) and 6(a) of this 13D/A are hereby incorporated by reference in this Item 5.

N/A

1,099,335 Shares owned by JM Holdings I are covered by the Prepaid Forward Contract. The Prepaid Forward Contract obligates JM Holdings I to deliver to the buyer under the Prepaid Forward Contract, on each Valuation Date, at JM Holdings I's option, up to 100% of the number of Shares pledged for the applicable component or an equivalent amount of cash. JM Holdings I pledged an aggregate of 1,099,335 Shares the ("Pledged Shares") to secure its obligations under the Prepaid Forward Contract, and currently retains ownership and voting rights in the Pledged Shares during the term of the pledge. The number of Shares to be potentially delivered to the buyer on each Valuation Date (or on which to base the amount of cash to be delivered to the buyer on such Valuation Date) is to be determined as follows: (a) if the VWAP of Shares on the Valuation Date for the applicable Tranche 1 Component or Tranche 2 Component (each, a "Valuation Price") is less than or equal to $97.3535 (the "Tranche 1 Floor Price") or $157.3441 (the "Tranche 2 Floor Price," and each of the Tranche 1 Floor Price and Tranche 2 Floor Price, a "Floor Price"), respectively, then JM Holdings I will deliver to the buyer all of the Pledged Shares for the applicable component; (b) if such Valuation Price for the Tranche 1 Component or Tranche 2 Component is greater than the Tranche 1 Floor Price or Tranche 2 Floor Price, respectively, but less than or equal to $127.6413 (the "Tranche 1 Cap Price") or $243.0093 (the "Tranche 2 Cap Price," and each of the Tranche 1 Cap Price and Tranche 2 Cap Price, a "Cap Price"), respectively, then JM Holdings I will deliver to the buyer the number of Shares equal to 100% of the Pledged Shares for the applicable component multiplied by the quotient of the applicable Floor Price divided by such Valuation Price and (c) if such Valuation Price for the Tranche 1 Component or Tranche 2 Component exceeds the Tranche 1 Cap or Tranche 2 Cap Price, respectively, then JM Holdings I will deliver to the buyer the number of Shares equal to 100% of Pledged Shares for the applicable component multiplied by the quotient of (x) the applicable Floor Price plus such excess divided by (y) such Valuation Price. Except as set forth above, JM Holdings I retains beneficial ownership of the Pledged Shares and rights related thereto, including voting power with respect thereto.

Exhibit 99.1 Variable Share Forward Transaction Amendment No. 3 Agreement dated August 18, 2025 by and between Jorge Mas Holdings I, LLC and Bank of America, N.A.