Sec Form 4 Filing - GUSTAFSON KURT A @ OmniAb, Inc. - 2023-12-07

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 GUSTAFSON KURT A 2. Issuer Name and Ticker or Trading Symbol OmniAb, Inc. [ OABI] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Executive VP, Finance & CFO (Last) (First) (Middle) 5980 HORTON STREET,, STE 600 3. Date of Earliest Transaction (MM/DD/YY) 12/07/2023 (Street) EMERYVILLE, CA94608 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 12/07/2023 M 46,503 A 174,786 ( 2 ) D Common Stock 12/07/2023 F 16,081 ( 3 ) D $ 4.85 158,705 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 Restricted Stock Units $ 0 ( 4 ) ( 4 ) ( 4 ) Common Stock 46,498 46,498 D Restricted Stock Units $ 0 ( 5 ) ( 5 ) ( 5 ) Common Stock 139,504 186,002 D Restricted Stock Units $ 0 ( 6 ) ( 6 ) ( 6 ) Common Stock 40,625 226,627 D Restricted Stock Units $ 0 ( 1 ) 12/07/2023 M 46,503 ( 1 ) ( 1 ) Common Stock 46,503 $ 0 180,124 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other GUSTAFSON KURT A 5980 HORTON STREET, STE 600 EMERYVILLE, CA94608 Executive VP, Finance & CFO Signatures By: /s/ Charles S. Berkman, Attorney-In-Fact For: Kurt A. Gustafson 12/11/2023 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents Restricted Stock Units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's Common Stock. The RSUs shall vest in three substantially equal annual installments beginning on December 07, 2023, subject to the Reporting Person's continued service to the Issuer through each such vesting date. ( 2 )The total includes 8,334 shares acquired on May 31, 2023, and 11,160 shares acquired on November 30, 2023, through the Issuer's Employee Stock Purchase Plan(ESPP). ( 3 )Represents shares withheld to satisfy tax withholding obligations upon the vesting of previously reported restricted stock units ("RSUs"). ( 4 )Represents RSUs previously reported in Table I. Each RSU represents a contingent right to receive one share of the Issuer's Common Stock. Vesting occurs in two substantially equal annual installments, beginning April 1st, 2024, subject to the Reporting Person's continued service to the Issuer through each such vesting date. ( 5 )Represents RSUs previously reported in Table I. Each RSU represents a contingent right to receive one share of the Issuer's Common Stock. Vesting occurs in three substantially equal annual installments, beginning December 7th, 2023, subject to the Reporting Person's continued service to the Issuer through each such vesting date. ( 6 )Represents RSUs previously reported in Table I. Each RSU represents a contingent right to receive one share of the Issuer's Common Stock. Vesting occurs in three substantially equal annual installments, beginning April 7th, 2024, subject to the Reporting Person's continued service to the Issuer through each such vesting date.

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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