Sec Form 4 Filing - Fortress Biotech, Inc. @ Checkpoint Therapeutics, Inc. - 2025-05-29

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 Fortress Biotech, Inc. 2. Issuer Name and Ticker or Trading Symbol Checkpoint Therapeutics, Inc. [ CKPT] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 1111 KANE CONCOURSE, SUITE 301 3. Date of Earliest Transaction (MM/DD/YY) 05/29/2025 (Street) BAY HARBOR ISLANDS, FL33154 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 $0.0001 05/29/2025 S 100,000 D $ 1.29 ( 1 ) 6,122,249 D COMMON STOCK, PAR VALUE $0.0001 05/30/2025 D 6,122,249 D $ 4.1 ( 2 ) 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 CLASS A COMMON STOCK, PAR VALUE $0.0001 $ 4.1 05/30/2025 D 700,000 ( 2 )( 3 ) ( 2 )( 3 ) Common Stock 700,000 $ 0 0 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Fortress Biotech, Inc. 1111 KANE CONCOURSE SUITE 301 BAY HARBOR ISLANDS, FL33154 X Signatures /s/ Samuel Berry, Attorney-in-Fact 06/03/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On July 15, 2015, pursuant to the Fortress Biotech, Inc. Long Term Incentive Plan, the Reporting Person issued warrants to purchase 500,000 shares of Issuer common stock (out of the Reporting Person's holdings in the Issuer) to each of Lindsay A. Rosenwald and Michael S. Weiss (collectively, the "Warrants"). Following a December 2022 reverse stock split by the Issuer, the Warrants became exercisable into 100,000 shares of Issuer common stock in the aggregate, with an exercise price of $1.29 per share. Dr. Rosenwald and Mr. Weiss exercised the Warrants on May 29, 2025. ( 2 )On March 9, 2025, the Issuer entered into an Agreement and Plan of Merger (the "Merger Agreement") by and among the Issuer, Sun Pharmaceutical Industries, Inc., a Delaware corporation ("Parent"), and Snoopy Merger Sub, Inc., a Delaware corporation and wholly owned subsidiary of Parent ("Merger Sub"). On May 30, 2025 (the "Closing Date"), Merger Sub merged with and into the Issuer pursuant to the Merger Agreement, with the Issuer continuing as the surviving corporation and a wholly owned subsidiary of Parent (the "Merger"). As a result of the Merger, each issued and outstanding share of Common Stock and Class A Common Stock that was previously held by the Reporting Person was automatically canceled and ceased to exist and was converted into the right to receive: (i) $4.10 in cash, without interest, and (ii) one non-tradable contingent value right (a "CVR"), which represents the right to receive a contingent cash payment of up to $0.70 upon the achievement of a specified milestone. ( 3 )Each share of Class A Common Stock had no expiration date and was convertible at any time at the option of Reporting Person into one share of the Issuer's Common Stock.

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

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