Exhibit 99.3
Unaudited Pro Forma Condensed Combined Financial Information
Introduction
On July 1, 2024 (the
Closing Date), Six Flags Entertainment Corporation (formerly known as CopperSteel HoldCo, Inc.) completed the previously announced merger transaction contemplated by the Agreement and Plan of Merger, dated as of November 2, 2023
(the Merger Agreement), by and among CopperSteel HoldCo, Inc. (CopperSteel), Cedar Fair, L.P. (the Partnership, Cedar Fair or Former 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 the Partnership (the Cedar Fair First Merger), with
the Partnership continuing as the surviving entity (the Cedar Fair Surviving Entity) and a direct subsidiary of CopperSteel, (ii) the Cedar Fair Surviving Entity was subsequently merged with and into CopperSteel (the Cedar
Fair Second Merger and together with the Cedar Fair First Merger, the Cedar Fair Mergers), with CopperSteel continuing as the surviving corporation, and (iii) Former Six Flags merged with and into CopperSteel (the Six
Flags Merger and together with the Cedar Fair Mergers, the Mergers), with CopperSteel continuing as the surviving corporation. Upon the consummation of the Mergers, the separate legal existences of Copper Merger Sub, the
Partnership and Former Six Flags ceased, and CopperSteel changed its name to Six Flags Entertainment Corporation. CopperSteel will be referred to as the Company or Six Flags in the unaudited pro forma condensed
combined financial information hereafter.
The Company was formed by Former Six Flags on October 24, 2023, for the purpose of
effecting the Mergers and prior to the Mergers was jointly owned by Former Six Flags and Former Cedar Fair. Prior to the effectiveness of the Mergers, the Company had not conducted any activities other than those incidental to its formation and the
matters contemplated by the Merger Agreement in connection with the Mergers and had nominal assets and liabilities. The Company is the successor corporation to Former Six Flags and Former Cedar Fair. Following the closing of the Mergers (the
Closing), the Company is headquartered in Charlotte, North Carolina, and its shares of common stock, par value $0.01 per share (the Six Flags Common Stock), are listed on the New York Stock Exchange under the ticker symbol
FUN.
Upon completion of the Mergers, subject to certain exceptions, (i) each issued and outstanding unit of limited
partnership interest in Former Cedar Fair (each a Cedar Fair Unit and collectively, the Cedar Fair Units) was converted into the right to receive one (1) share of Six Flags Common Stock, as adjusted pursuant to the
Merger Agreement (the Former Cedar Fair Exchange Ratio), together with cash in lieu of fractional shares of Six Flags Common Stock, without interest and (ii) each issued and outstanding share of common stock, par value $0.025 per
share, of Former Six Flags (the Former Six Flags Common Stock) was converted into the right to receive 0.5800 shares of Six Flags Common Stock, as adjusted pursuant to the Merger Agreement (the Former Six Flags Exchange
Ratio), together with cash in lieu of fractional shares of Six Flags Common Stock, without interest.
Terms such as Six Flags Stock
Options, Six Flags Restricted Shares, Six Flags RSU Awards, Six Flags Deferred Share Unit Awards, Six Flags PSU Awards, the CopperSteel Stock Options, the CopperSteel Restricted Shares, the CopperSteel RSU Awards, the CopperSteel PSU Awards, Cedar
Fair Bonds, Cedar Fair Unit-Settled Deferred Units, Special Dividend and Consent Payment used within the following unaudited pro forma condensed combined financial information shall have the same meanings ascribed thereto as in the Companys
proxy statement/prospectus, which is part of the Companys Registration Statement on Form S-4 (File No. 333-276255), initially filed by the Company on
December 22, 2023 and declared effective by the Securities and Exchange Commission on January 31, 2024 (the proxy statement/prospectus). Any references to Six Flags, Cedar Fair or CopperSteel
in the proxy statement/prospectus is now referenced within the below unaudited pro forma condensed combined financial information as Former Six Flags, Former Cedar Fair, and Six Flags, respectively.
On May 1, 2024, Former Cedar Fair, Canadas Wonderland Company (Canadas Wonderland), Millennium Operations LLC
(Millennium), the other subsidiary borrowers party thereto, the guarantors party thereto, the lenders party thereto and Wells Fargo Bank, National Association, as administrative agent and collateral agent (the Administrative
Agent), entered into a new credit agreement (the 2024 Credit Agreement),