Six Flags Entertainment Corporation/NEW

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

(Mark One)

For the quarterly period ended September 28, 2025

or

For the transition period from to .

Commission File Number:001-42157

(Exact name of registrant as specified in its charter)

8701 Red Oak Blvd., Charlotte, North Carolina 28217

(Address of principal executive offices) (Zip Code)

(704)414-4700

(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. x Yes ☐ No

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). x Yes ☐ No

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of "large accelerated filer," "accelerated filer," "smaller reporting company," and "emerging growth company" in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).☐ Yesx No

Indicate the number of shares outstanding of each of the issuer's classes of common stock, as of the latest practicable date.

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EXPLANATORY NOTE

On July 1, 2024 (the “Closing Date”), Six Flags Entertainment Corporation (formerly known as CopperSteel HoldCo, Inc.) (the “Combined Company”) completed the previously announced merger of equals transaction contemplated by the Agreement and Plan of Merger, dated as of November 2, 2023 (the “Merger Agreement”), by and among the Combined Company (then, CopperSteel HoldCo, Inc.), Cedar Fair, L.P. (“Cedar Fair”), Six Flags Entertainment Corporation (“Former Six Flags”) and CopperSteel Merger Sub, LLC (“Copper Merger Sub”). Pursuant to the Merger Agreement, (i) Copper Merger Sub was merged with and into Cedar Fair (the “Cedar Fair First Merger”), with Cedar Fair continuing as the surviving entity (the “Cedar Fair Surviving Entity”) and a direct subsidiary of the Combined Company, (ii) the Cedar Fair Surviving Entity was subsequently merged with and into the Combined Company (the “Cedar Fair Second Merger” and together with the Cedar Fair First Merger, the “Cedar Fair Mergers”), with the Combined Company continuing as the surviving corporation, and (iii) Former Six Flags merged with and into the Combined Company (the “Six Flags Merger” and together with the Cedar Fair Mergers, the “Mergers”), with the Combined Company continuing as the surviving corporation. Upon the consummation of the Mergers, the separate legal existences of each of Copper Merger Sub, Cedar Fair and Former Six Flags ceased, and the Combined Company changed its name to “Six Flags Entertainment Corporation”. The Combined Company trades on the New York Stock Exchange under the ticker symbol "FUN".

The Six Flags Merger was accounted for as a business combination under Accounting Standards Codification 805, Business Combinations, using the acquisition method of accounting, and Cedar Fair has been determined to be the accounting acquirer and the predecessor for financial statement purposes. The results of Former Six Flags are included in the Combined Company's results from the Closing Date forward. Accordingly, financial results and disclosures as of September 28, 2025, December 31, 2024 and September 29, 2024, for the three and nine months ended September 28, 2025, and for the three months ended September 29, 2024 reflect the Combined Company's operations. Financial results and disclosures for the nine months ended September 29, 2024 include only Cedar Fair's results before giving effect to the Mergers through June 30, 2024 and include Combined Company results from July 1, 2024 through September 29, 2024.

For purposes of this Quarterly Report on Form 10-Q, references to the "Combined Company" and the "Company" are to Cedar Fair, Former Six Flags and Copper Merger Sub after giving effect to the Mergers. References to "Cedar Fair," "Former Cedar Fair," or the "Partnership" are to Cedar Fair prior to the Mergers.