Sec Form 4 Filing - Machado Patrick @ ALUMIS INC. - 2025-05-21

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 Machado Patrick 2. Issuer Name and Ticker or Trading Symbol ALUMIS INC. [ ALMS] 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 ALUMIS INC., 280 EAST GRAND AVENUE 3. Date of Earliest Transaction (MM/DD/YY) 05/21/2025 (Street) SOUTH SAN FRANCISCO, CA94080 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 05/21/2025 A 7,064 A 7,064 I By Trust ( 2 )

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) ( 3 ) $ 9.26 ( 4 ) 05/21/2025 A 44,364 ( 5 ) 06/06/2034 Class A Common Stock 44,364 ( 1 ) 44,364 D Stock Option (Right to Buy) ( 6 ) $ 37.39 ( 4 ) 05/21/2025 A 11,189 ( 5 ) 05/03/2033 Class A Common Stock 11,189 ( 1 ) 11,189 D Stock Option (Right to Buy) ( 7 ) $ 12.21 ( 4 ) 05/21/2025 A 41,499 ( 5 ) 11/20/2032 Class A Common Stock 41,499 ( 1 ) 41,499 D Stock Option (Right to Buy) ( 8 ) $ 12.21 ( 4 ) 05/21/2025 A 13,804 ( 5 ) 11/20/2032 Class A Common Stock 13,804 ( 1 ) 13,804 D Stock Option (Right to Buy) ( 9 ) $ 1.6 ( 4 ) 05/21/2025 A 19,528 ( 5 ) 07/25/2031 Class A Common Stock 19,528 ( 1 ) 19,528 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Machado Patrick C/O ALUMIS INC. 280 EAST GRAND AVENUE SOUTH SAN FRANCISCO, CA94080 X Signatures /s/ Sara Klein, Attorney-in-Fact 05/23/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On February 6, 2025, the Issuer entered into an Agreement and Plan of Merger (as amended on April 20, 2025, the "Merger Agreement") with ACELYRIN, Inc., a Delaware corporation ("ACELYRIN"), and Arrow Merger Sub, Inc., a Delaware corporation and wholly owned subsidiary of Issuer ("Merger Sub"). Pursuant to the Merger Agreement, on May 21, 2025, Merger Sub merged with and into ACELYRIN (the "Merger"), with ACELYRIN surviving as a wholly owned subsidiary of Issuer. At the effective time of the Merger (the "Effective Time"), each share of common stock, par value $0.00001 per share, of ACELYRIN issued and outstanding was converted into the right to receive 0.4814 (the "Exchange Ratio") shares of voting common stock of Issuer, par value $0.0001 per share, and cash in lieu of any fractional shares. ( 2 )Shares held directly by Patrick Machado Revocable Trust, Patrick Machado, TEE, for which the Reporting Person serves as trustee. ( 3 )Received in the Merger in exchange for an employee stock option to acquire 92,158 shares of ACELYRIN common stock for $4.46 per share. ( 4 )Pursuant to the Merger Agreement, at the Effective Time each stock option that was outstanding and unexercised immediately prior to the Effective Time with a per share exercise price of $18.00 or less was assumed by Issuer and converted into an option to purchase a number of shares of Issuer Common Stock equal to (i) the number of shares subject to the option immediately prior to the Effective Time, multiplied by (ii) the Exchange Ratio, with any fractional shares rounded down to the nearest whole share, which stock option shall have an exercise price equal to (i) the per share exercise price for shares subject to the corresponding ACELYRIN stock option immediately prior to the Effective Time, divided by (ii) the Exchange Ratio, rounded up to the nearest whole cent. ( 5 )Stock Option is fully vested and exercisable. ( 6 )Received in the Merger in exchange for an employee stock option to acquire 23,243 shares of ACELYRIN common stock for $18.00 per share. ( 7 )Received in the Merger in exchange for an employee stock option to acquire 86,206 shares of ACELYRIN common stock for $5.8766 per share. ( 8 )Received in the Merger in exchange for an employee stock option to acquire 28,675 shares of ACELYRIN common stock for $5.8766 per share. ( 9 )Received in the Merger in exchange for an employee stock option to acquire 40,567 shares of ACELYRIN common stock for $0.7683 per share.

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).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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