Sec Form 3 Filing - Donati Piergiorgio @ AC Immune SA - 2026-03-20

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 Donati Piergiorgio 2. Issuer Name and Ticker or Trading Symbol AC Immune SA [ ACIU] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chief Operating Officer (Last) (First) (Middle) EPFL INNOVATION PARK, BUILDING B 3. Date of Earliest Transaction (MM/DD/YY) 03/20/2026 (Street) LAUSANNE1015 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 Shares 141,120 ( 1 ) 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 Share Option (right to buy) $ 9.5 ( 2 ) 07/05/2028 Common Shares 7,200 D Share Option (right to buy) $ 5.39 ( 2 ) 06/27/2029 Common Shares 41,322 D Share Option (right to buy) $ 6.95 ( 2 ) 06/25/2030 Common Shares 34,562 D Share Option (right to buy) $ 7.23 ( 2 ) 06/24/2031 Common Shares 28,463 D Share Option (right to buy) $ 3.15 ( 2 ) 06/23/2032 Common Shares 22,050 D Share Option (right to buy) $ 2.03 ( 2 ) 12/31/2032 Common Shares 66,667 D Share Option (right to buy) $ 3.99 ( 3 ) 12/31/2033 Common Shares 27,607 D Share Option (right to buy) $ 2.91 ( 4 ) 12/31/2034 Common Shares 61,538 D Share Option (right to buy) $ 3.03 ( 5 ) 12/31/2035 Common Shares 89,552 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Donati Piergiorgio EPFL INNOVATION PARK, BUILDING B LAUSANNE1015 Chief Operating Officer Signatures /s/ Matthias Maurer, attorney-in-fact for Piergiorgio Donati 03/20/2026 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Includes 136,620 common shares underlying outstanding restricted share units. ( 2 )The share option is fully vested. ( 3 )The share option will vest in twelve substantially equal quarterly installments beginning on March 31, 2024. ( 4 )The share option will vest in twelve substantially equal quarterly installments beginning on March 31, 2025. ( 5 )The share option will vest in twelve substantially equal quarterly installments beginning on March 31, 2026.

Remarks: Exhibit 24 - Power of Attorney

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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