CECO环保美股招股说明书(2026-04-23版)

MERGER PROPOSED — YOUR VOTE IS VERY IMPORTANT On behalf of the boards of directors of CECO Environmental Corp. (“CECO” or “Parent”) and Thermon Group Holdings,Inc. (“Thermon” or the “Company”), we are pleased to enclose the accompanying joint proxy statement/prospectus relating tothe proposed combination of CECO and Thermon. We are requesting that you take certain actions as a CECO or Thermonstockholder. On February23, 2026, CECO, Longhorn Merger Sub, Inc., a Delaware corporation and a direct wholly owned subsidiary ofCECO (“Merger Sub Inc.”), Longhorn Merger Sub LLC, a Delaware limited liability company and a direct wholly ownedsubsidiary of CECO (“Merger Sub LLC”), and Thermon entered into an Agreement and Plan of Merger (as may be amendedfrom time to time, the “merger agreement”), pursuant to which CECO will acquire Thermon through a series of mergers. In the first merger, Merger Sub Inc. will merge with and into Thermon, with Thermon surviving as a wholly ownedsubsidiary of CECO (the “first merger” and the surviving entity, the “surviving corporation”). Immediately following the firstmerger, the surviving corporation will merge with and into Merger Sub LLC, with Merger Sub LLC continuing as the survivingentity (the “second merger” and, together with the first merger, the “mergers,” and the surviving entity, the “survivingcompany”). The first merger will become effective at such time as the parties shall agree and shall specify in the certificate ofmerger filed with the Secretary of State of the State of Delaware (the “effective time”). The second merger will become effectiveone minute after the effective time, or at such later time as the parties shall agree and shall specify in the certificate of mergerfor the second merger (the “second merger effective time”). In the first merger, each share of common stock, par value $0.001 per share, of Thermon (“Thermon common stock”) (otherthan certain excluded shares and dissenting shares) will be converted into the right to receive, at the election of the holder, oneof the following forms of merger consideration, subject, in the case of any cash election or stock election, to proration asdescribed in the merger agreement: •••Mixed Election: 0.6840 shares of common stock, par value $0.01 per share, of CECO (“CECO common stock”) and$10.00 in cash, without interest (the “mixed consideration”). Shares for which no election is made will be treated asmixed election shares.Cash Election: $63.89 in cash per share, without interest (the “cash consideration”).Stock Election: 0.8110 shares of CECO common stock per share (the “stock consideration”). Importantly, although Thermon stockholders may elect among these three options, the aggregate amount of cash and stockto be paid by CECO in the mergers is fixed. Based on the number of shares of Thermon common stock expected to beoutstanding at closing, the total cash payable by CECO is capped at approximately $334million and the total CECO sharesissuable is capped at approximately 22.9million shares. Cash and stock needed to pay the mixed consideration (the default forstockholders who make no election) are funded first from each pool, and only the remainder is available to satisfy cash electionsand stock elections. Accordingly, all elections for all-cash or all-stock consideration are subject to mandatory proration to theextent cumulative elections exceed the amounts available, and stockholders who made those elections may receive a proratedamount of their chosen consideration and the balance in the alternative form. The mixed consideration is not subject toproration. Following the closing of the mergers, it is anticipated that persons who were stockholders of CECO or Thermonimmediately prior to the mergers will own approximately 62.5% and 37.5% of the combined company on a fully diluted basis,respectively. The actual ownershippercentages will depend on the number of shares of CECO common stock and Thermoncommon stock issued and outstanding immediately prior to the effective time. CECO and Thermon will each hold meetings of their respective stockholders in connection with the mergers (as may beadjourned or postponed from time to time, respectively, the “CECO annual meeting” and the “Thermon special meeting”). At the CECO annual meeting, CECO stockholders will be asked to consider and vote various proposals described herein,including on a proposal to approve the issuance of shares of CECO common stock in connection with the first merger and othershares of CECO common stock to be issued in the mergers or reserved for issuance in connection with the mergers (the “CECOstock issuance proposal”). The CECO board of directors unanimously recommends that CECO stockholders vote “FOR” the CECO stock issuanceproposal and the other proposals described herein. At the Thermon special meeting, Thermon stockholders will be asked to consider and vote on proposals to (1)adopt themerger agreement (the “Thermon merger proposal”) and (2)a