Sec Form 3 Filing - Tom Penny @ Equillium, Inc. - 2024-03-06

FORM 3 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 Tom Penny 2. Issuer Name and Ticker or Trading Symbol Equillium, Inc. [ EQ] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Principal Accounting Officer (Last) (First) (Middle) 2223 AVENIDA DE LA PLAYA, SUITE 105 3. Date of Earliest Transaction (MM/DD/YY) 03/06/2024 (Street) LA JOLLA, CA92037 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 33,857 D

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 Employee Stock Option (right to buy) $ 2.45 ( 2 ) ( 1 ) 01/30/2029 Common Stock 65,000 Employee Stock Option (right to buy) $ 2.45 ( 2 ) ( 1 ) 12/09/2029 Common Stock 45,000 D Employee Stock Option (right to buy) $ 5.03 ( 2 ) ( 1 ) 01/03/2031 Common Stock 40,000 D Employee Stock Option (right to buy) $ 3.86 ( 2 ) ( 1 ) 01/18/2032 Common Stock 60,000 D Employee Stock Option (right to buy) $ 2.52 ( 2 ) ( 1 ) 05/01/2032 Common Stock 40,000 D Employee Stock Option (right to buy) $ 1.06 ( 2 ) ( 1 ) 01/02/2033 Common Stock 100,000 D Employee Stock Option (right to buy) $ 0.73 ( 1 ) 01/01/2034 Common Stock 100,000 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Tom Penny 2223 AVENIDA DE LA PLAYA, SUITE 105 LA JOLLA, CA92037 Principal Accounting Officer Signatures /s/ Penny Tom 03/06/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Twenty-five percent of the shares subject to the option vests on the first anniversary of the vesting commencement date, and the remainder vests in 36 equal monthly installments thereafter for the following three years. ( 2 )Effective as of August 14, 2023, the Company's board of directors approved the repricing of the options to an exercise price of $0.785 per share. However, if a repriced option is exercised prior to the Retention Period End Date (as defined in Item 5 of the Company's Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2023, filed with the SEC on August 9, 2023), or the optionholder's employment or service terminates under certain circumstances prior to the Retention Period End Date, the optionholder will be required to pay a premium price equivalent to the original exercise price per share of the repriced options. Such original exercise price per share is reflected in this column.

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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