AC Immune (ACIU) CEO Pfeifer logs 10,000-share sale in amended Form 4

Rhea-AI Filing Summary

AC Immune SA Chief Executive Officer Andrea Pfeifer sold 10,000 shares of the company’s stock in an open-market transaction. The amended filing clarifies that a prior report mistakenly showed this activity as a purchase and now correctly records it as a sale.

The shares were sold at a weighted average price of $3.1425, with individual trade prices ranging from $3.05 to $3.19. After the sale, Pfeifer directly owns 3,830,288 shares, including 1,921,005 common shares underlying outstanding restricted share units, and also has indirect ownership of 14,000 shares held by her spouse.

Insider Trade Summary 10b5-1

Net Seller: 10,000 shares ($31,425)

Net Sell 2 txns

Insider Pfeifer Andrea

Role Chief Executive Officer

Sold 10,000 shs ($31K)

Type	Security	Shares	Price	Value
Sale	Share	10,000	$3.1425	$31K
holding	Share	--	--	--

Holdings After Transaction: Share — 3,830,288 shares (Direct); Share — 14,000 shares (Indirect, By spouse)

Footnotes (1)

1. This Form 4/A amends the Form 4 filed on April 16, 2026, inadvertently reporting in column 3 a purchase of 10,000 shares on behalf of the reporting person. This amendment corrects that filing to reflect that the reporting person sold 10,000 shares. The price is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.05 to $3.19, inclusive. Includes 1,921,005 common shares underlying outstanding restricted share units.

Key Figures

Shares sold: 10,000 shares Weighted average sale price: $3.1425 per share Post-sale direct holdings: 3,830,288 shares +3 more

6 metrics

Shares sold 10,000 shares Open-market sale reported on Form 4/A

Weighted average sale price $3.1425 per share Sale on reported transaction date

Post-sale direct holdings 3,830,288 shares Direct ownership following transaction

RSU underlying shares 1,921,005 shares Common shares underlying outstanding restricted share units

Indirect holdings by spouse 14,000 shares Indirect ownership reported as by spouse

Sale price range $3.05–$3.19 per share Price range for multiple sale executions

Key Terms

Form 4/A, weighted average price, restricted share units, open-market sale, +1 more

5 terms

Form 4/A regulatory

"This Form 4/A amends the Form 4 filed on April 16, 2026"

Form 4/A is an amended filing that corrects or updates an earlier Form 4, the mandatory report that insiders (like company executives, directors, or large shareholders) must file when their ownership stakes change. Think of it as an edited receipt showing who bought or sold stock and when; investors use it to track insider confidence, detect potential conflicts, and spot trading patterns that might signal future company prospects.

weighted average price financial

"The price is a weighted average price. These shares were sold in multiple transactions"

Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.

restricted share units financial

"Includes 1,921,005 common shares underlying outstanding restricted share units"

Restricted share units (RSUs) are a promise from a company to give an employee or service provider actual shares or cash equal to the shares after certain conditions are met, typically staying with the company for a set time or hitting performance targets. Think of them like a time-locked gift card that becomes usable only after you’ve earned it. For investors, RSUs matter because they align employee incentives with company performance and can increase the number of shares outstanding over time, diluting existing ownership and affecting earnings per share.

open-market sale financial

"transaction_action": "open-market sale""

An open-market sale is when a shareholder sells existing shares directly on a public exchange to any willing buyer, rather than through a private deal. Think of it like putting goods on a busy market stall where price is set by supply and demand; for investors it matters because such sales increase available supply, can put short-term downward pressure on the stock price, and signal changes in liquidity or investor confidence.

indirect ownership financial

""direct_or_indirect": "I","nature_of_ownership": "By spouse""

Form 4 Insider Transactions: What Each Field Means →

SEC Form 4

FORM 4

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
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

X

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Pfeifer Andrea

(Last) (First) (Middle)

C/O AC IMMUNE SA

EPFL INNOVATION PARK BUILDING B

(Street)

LAUSANNE 1015

(City) (State) (Zip)

SWITZERLAND

(Country)

2. Issuer Name and Ticker or Trading Symbol
AC Immune SA [ ACIU ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Executive Officer

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
04/15/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)
04/16/2026

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	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
Share	04/15/2026		S(1)		10,000	D	$3.1425(2)	3,830,288(3)	D
Share								14,000	I	By spouse

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 (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	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 (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (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: 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

Explanation of Responses:

1. This Form 4/A amends the Form 4 filed on April 16, 2026, inadvertently reporting in column 3 a purchase of 10,000 shares on behalf of the reporting person. This amendment corrects that filing to reflect that the reporting person sold 10,000 shares.

2. The price is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.05 to $3.19, inclusive.

3. Includes 1,921,005 common shares underlying outstanding restricted share units.

	Matthias Maurer	04/16/2026
	** Signature of Reporting Person	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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)

FAQ

What did AC Immune (ACIU) CEO Andrea Pfeifer report in this amended Form 4?

Andrea Pfeifer reported an open-market sale of 10,000 AC Immune shares. The amended filing corrects an earlier report that had mistakenly classified the transaction as a purchase instead of a sale, aligning the disclosure with the actual trading activity.

At what price did the AC Immune (ACIU) CEO sell the 10,000 shares?

The 10,000 AC Immune shares were sold at a weighted average price of $3.1425. Individual trades occurred at prices between $3.05 and $3.19 per share, reflecting multiple executions within that narrow trading range during the reported transaction.

How many AC Immune (ACIU) shares does the CEO hold after this sale?

After the sale, Andrea Pfeifer directly holds 3,830,288 AC Immune shares. This direct position includes 1,921,005 common shares underlying outstanding restricted share units, giving a clearer picture of her total equity-based interest reported in the filing.

Does the AC Immune (ACIU) CEO have any indirect share ownership reported?

Yes. In addition to her direct holdings, Andrea Pfeifer has indirect ownership of 14,000 AC Immune shares held by her spouse. The filing lists these shares separately as indirect ownership, providing transparency on family-related holdings associated with the CEO.

Why was this AC Immune (ACIU) Form 4/A filed as an amendment?

The Form 4/A was filed to correct the original Form 4, which had inadvertently reported the 10,000-share transaction as a purchase. The amendment clarifies that the transaction was actually a sale, ensuring the insider trading record is accurate and consistent.

How are restricted share units reflected in AC Immune (ACIU) CEO’s holdings?

The CEO’s direct holdings of 3,830,288 AC Immune shares include 1,921,005 common shares underlying outstanding restricted share units. This means a substantial portion of her reported interest comes from equity awards that convert into common shares under specified vesting conditions.