Sec Form 4 Filing - Huang Chieh E. @ Six Flags Entertainment Corp/OLD - 2024-07-01

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Huang Chieh E. 2. Issuer Name and Ticker or Trading Symbol Six Flags Entertainment Corp/OLD [ SIX] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O SIX FLAGS ENTERTAINMENT CORPORATION, 1000 BALLPARK WAY, SUITE 400 3. Date of Earliest Transaction (MM/DD/YY) 07/01/2024 (Street) ARLINGTON, TX76011 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock, par value $0.025 per share 07/01/2024 D 22,239 D 0 D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Huang Chieh E. C/O SIX FLAGS ENTERTAINME NT CORPORATION 1000 BALLPARK WAY, SUITE 400 ARLINGTON, TX76011 X Signatures /s/ Chieh E. Huang 07/01/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The reported securities include 7,980 shares of restricted stock (the "Restricted Stock") originally granted to the reporting person on May 10, 2024, and scheduled to vest one year from the date of grant, subject to the reporting person's continued service through such date. Pursuant to that certain Agreement and Plan of Merger, dated as of November 2, 2023, (the "Merger Agreement"), by and among the Issuer, Cedar Fair, L.P., CopperSteel HoldCo, Inc. (now known as Six Flags Entertainment Corporation) ("HoldCo") and CopperSteel Merger Sub, LLC, the Restricted Stock vested and each share of Common Stock was disposed of in exchange for .5800 shares of Holdco common stock.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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