Investor Presentaiton

NOTICE TO INVESTORS This presentation (and oral statements regarding the subject matter of this presentation) includes forward-looking statements intended to qualify under the "safe harbor" from liability established by the Private Securities Litigation Reform Act of 1995. These forward-looking statements include any statements reflecting Quanta's expectations, intentions, strategies, assumptions, plans or beliefs about future events or performance or that do not solely relate to historical or current facts. Forward-looking statements involve certain risks, uncertainties and assumptions that are difficult to predict or beyond Quanta's control, and actual results may differ materially from those expected, implied or forecasted by our forward-looking statements due to inaccurate assumptions and known and unknown risk and uncertainties. For additional information concerning some of the risks, uncertainties, assumptions and other factors that could affect our forward-looking statements, please refer to Quanta's Annual Report on Form 10-K for the year ended December 31, 2022, Quarterly Reports on Form 10-Q for the quarters ended March 31, 2023, June 30, 2023 and September 30, 2023 and other documents filed with the Securities and Exchange Commission, which are available on our website (www.quantaservices.com), as well as the risks, uncertainties and assumptions identified in this presentation. Investors and analysts should not place undue reliance on Quanta's forward-looking statements, which are current only as of the date of this presentation. Quanta does not undertake and expressly disclaims any obligation to update or revise any forward-looking statements to reflect events or circumstances after the date of this presentation or otherwise, and Quanta expressly disclaims any written or oral statements made by any third party regarding the subject matter of this presentation. Additionally, any financial projections in this presentation are forward-looking statements that are based on assumptions that are inherently subject to significant uncertainties and contingencies, many of which are beyond Quanta's control. While such projections are necessarily speculative, Quanta believes that the preparation of prospective financial information involves increasingly higher levels of uncertainty the further out the projection extends from the date of preparation. The assumptions and estimates underlying such projected results are inherently uncertain and are subject to a wide variety of significant business, economic and competitive risks and uncertainties that could cause actual results to differ materially from those contained in the projections. The inclusion of financial information or projections in this presentation should not be regarded as an indication that Quanta considered or consider the information or projections to be a reliable prediction of future events. Certain information may be provided in this presentation that includes financial measurements that are not required by, or presented in accordance with, generally accepted accounting principles (GAAP). These non- GAAP financial measures should not be considered as alternatives to GAAP financial measures, such as net income attributable to common stock and cash flow provided by operating activities, and may be calculated differently from, and therefore may not be comparable to, similarly titled measures used by other companies. For a reconciliation to the most directly comparable GAAP financial measures, please refer to the accompanying reconciliation tables. The information contained in this document has not been audited by any independent auditor. This presentation is prepared as a convenience for securities analysts and investors and may be useful as a reference tool. Quanta may elect to modify the format or discontinue publication at any time, without notice to securities analysts or investors. QUANTA Page 2

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