Capital Markets Overview

Forward-Looking Information Non-GAAP and Supplementary Financial Measures The information in this presentation includes certain forward-looking statements. Although these forward-looking statements are based on currently available competitive, financial and economic data and operating plans, they are subject to risks and uncertainties. In addition to events beyond Aecon's control, there are factors which could cause actual or future results, performance or achievements to differ materially from those expressed or inferred herein including risks associated with an investment in the common shares of Aecon and the risks related to Aecon's business. Such factors include but are not limited to: the timing of projects, unanticipated costs and expenses, the ability to recognize and adequately respond to climate change concerns or public and governmental expectations on climate matters, Aecon's assessment of the risks and opportunities related to its industry's transition to a lower-carbon economy, Aecon's expectations regarding legal proceedings to which Aecon is a party, general market and industry conditions and operational and reputational risks, including large project risk and contractual factors and risks relating to the COVID 19 pandemic. Risk factors are discussed in greater detail in Section 13 - "Risk Factors" in the 2020 Annual MD&A dated February 25, 2021 and in the Annual Information Form filed on February 26, 2021, both of which are available on the System for Electronic Document Analysis and Retrieval ("SEDAR") at www.sedar.com. Other important factors, in addition to those discussed in this document, could affect the future results of Aecon and could cause its results to differ materially from those expressed in any forward-looking statements. Forward-looking statements may include, without limitation, statements regarding the operations, business, financial condition, expected financial results, performance, prospects, ongoing objectives, strategies and outlook for Aecon. Forward-looking statements may in some cases be identified by words such as "will", "plans", "believes", "expects", "anticipates", "estimates", "projects", "intends", "should" or the negative of these terms, or similar expressions. Except as required by applicable securities laws, forward-looking statements speak only as of the date on which they are made and Aecon undertakes no obligation to publicly update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by applicable law. ACCON The presentation contains certain non-GAAP and supplementary financial measures, as well as non- GAAP ratios to assist readers in understanding the Company's performance (GAAP refers to Canadian Generally Accepted Accounting Principles). These measures do not have any standardized meaning and therefore are unlikely to be comparable to similar measures presented by other issuers and should not be considered in isolation or as a substitute for measures of performance prepared in accordance with GAAP. Management uses these non-GAAP and supplementary financial measures, as well as certain non- GAAP ratios to analyze and evaluate operating performance. Aecon also believes the financial measures defined below are commonly used by the investment community for valuation purposes, and are useful complementary measures of profitability, and provide metrics useful in the construction industry. Throughout this presentation, the following terms are used, which are not found in the Chartered Professional Accountants of Canada Handbook and do not have a standardized meaning under GAAP: "Adjusted EBITDA", "Equity Project EBITDA", "Backlog", "Adjusted EBITDA margin", "Gross Profit Margin". Refer to Section 4 “Non-GAAP and Supplementary Financial Measures" in the Company's Q3 2021 Management's Discussion and Analysis ("MD&A") available through SEDAR at www.sedar.com for the definitions of non-GAAP and supplementary financial measures as well as non-GAAP ratios used in this presentation. Refer to Section 9 “Quarterly Financial Data" in the Company's Q3 2021 MD&A for a quantitative reconciliation of the above-mentioned measures to the most comparable financial measures presented in the primary financial statements of the Company. 2

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