Sec Form 4 Filing - Yang Taiyin @ Kronos Bio, Inc. - 2025-06-20

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 Yang Taiyin 2. Issuer Name and Ticker or Trading Symbol Kronos Bio, Inc. [ KRON] 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 KRONOS BIO, INC., 301 BINNEY STREET, 2ND FLOOR EAST 3. Date of Earliest Transaction (MM/DD/YY) 06/20/2025 (Street) CAMBRIDGE, MA02142 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 06/20/2025 U 11,333 ( 1 ) ( 2 ) D $ 0.57 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 Stock Option (Right to Buy) $ 28.58 06/20/2025 D 41,200 ( 3 ) 03/24/2031 Common Stock 41,200 $ 0 0 D Stock Option (Right to Buy) $ 24.18 06/20/2025 D 5,150 ( 3 ) 06/21/2031 Common Stock 5,150 $ 0 0 D Stock Option (Right to Buy) $ 3.53 06/20/2025 D 17,000 ( 3 ) 06/21/2032 Common Stock 17,000 $ 0 0 D Stock Option (Right to Buy) $ 1.48 06/20/2025 D 34,000 ( 3 ) 06/21/2033 Common Stock 34,000 $ 0 0 D Stock Option (Right to Buy) $ 0.95 06/20/2025 D 34,000 ( 3 ) 06/24/2034 Common Stock 34,000 $ 0 0 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Yang Taiyin C/O KRONOS BIO, INC. 301 BINNEY STREET, 2ND FLOOR EAST CAMBRIDGE, MA02142 X Signatures /s/ Taiyin Yang 06/20/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Disposed of pursuant to the Agreement and Plan of Merger (the "Merger Agreement"), dated as of May 1, 2025, by and among Kronos Bio, Inc. (the "Issuer"), Concentra Biosciences, LLC ("Parent") and Concentra Merger Sub IV, Inc., a wholly owned subsidiary of Parent ("Merger Sub"). On June 18, 2025, Parent and Merger Sub completed a tender offer pursuant to the terms of the Merger Agreement for all outstanding shares of common stock of the Issuer (each, a "Share") for an offer price of (i) $0.57 per Share in cash (the "Cash Amount"), and (ii) one non-transferable contractual contingent value right (each, a "CVR"), subject to and in accordance with the terms of the Contingent Value Rights Agreement (the "CVR Agreement"), in each case, without interest, and subject to any applicable withholding taxes (the Cash Amount plus one CVR, collectively, the "Offer Price").[continues to Footnote 2] ( 2 )[continues from Footnote 1] Merger Sub thereafter merged with and into the Issuer, with the Issuer continuing as the surviving corporation and a wholly owned subsidiary of Parent (the "Merger"). At the effective time of the Merger, each issued and outstanding Share (other than any Excluded Shares (as such term is defined in the Merger Agreement)) was cancelled in exchange for the right to receive the Offer Price. ( 3 )As of immediately prior to and conditioned upon the effective time of the effective time of the Merger, pursuant to the Merger Agreement, each outstanding option to purchase Shares (each, an "Option") became fully vested and exercisable, and to the extent not exercised prior to the effective time of the Merger, was cancelled and converted into the right to receive (a) an amount in cash (without interest and subject to deduction for any required withholding tax) equal to the product of (1) the excess, if any, of the Cash Amount over the exercise price per share of each such Option and (2) the number of Shares underlying such Option immediately prior to the effective time of the Merger and (b) one CVR in respect of each Share underlying such Option; provided, however, that if the exercise price per Share of any Option was equal to or greater than the Cash Amount that was then outstanding it was cancelled for no consideration.

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