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Form 3 Sensei Biotherapeutics, For: Jun 12 Filed by: Hahn Stephen M.

June 16, 2026 4:19 PM
FORM 3 UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940
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1. Name and Address of Reporting Person *
Hahn Stephen M.

(Last) (First) (Middle)
C/O FAETH THERAPEUTICS, INC.
701 TILLERY STREET #12 #1010

(Street)
AUSTIN TX 78702

(City) (State) (Zip)
2. Date of Event Requiring Statement (Month/Day/Year)
06/12/2026
3. Issuer Name and Ticker or Trading Symbol
Sensei Biotherapeutics, Inc. [ FTH ]
4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
X Director 10% Owner
Officer (give title below) Other (specify below)
5. If Amendment, Date of Original Filed (Month/Day/Year)
6. Individual or Joint/Group Filing (Check Applicable Line)
X Form filed by One Reporting Person
Form filed by More than One Reporting Person
Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4) 2. Amount of Securities Beneficially Owned (Instr. 4) 3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 4. Nature of Indirect Beneficial Ownership (Instr. 5)
Table II - Derivative Securities Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4) 2. Date Exercisable and Expiration Date (Month/Day/Year) 3. Title and Amount of Securities Underlying Derivative Security (Instr. 4) 4. Conversion or Exercise Price of Derivative Security 5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 6. Nature of Indirect Beneficial Ownership (Instr. 5)
Date Exercisable Expiration Date Title Amount or Number of Shares
Series B Preferred Stock (1) (2) (3) (2) (3) Common Stock 44,763 (2) (3) (2) (3) D
Explanation of Responses:
1. Subject to certain conditions set forth in the Certificate of Designation of Preferences, Rights and Limitations of the Series B Preferred Stock, each share of Series B Preferred Stock is convertible into 1,000 shares of the Issuer's Common Stock and has no expiration date.
2. Pursuant to February 17, 2026 Agreement and Plan of Merger (the "Merger Agreement"), by and among the Issuer, Sapphire First Merger Sub, Inc., a Delaware corporation and a wholly owned subsidiary of the Issuer ("First Merger Sub"), Sapphire Second Merger Sub, LLC, a Delaware limited liability company and wholly owned subsidiary of the Issuer ("Second Merger Sub"), Faeth Holdings Therapeutics, Inc. ("HoldCo") and Faeth Therapeutics, LLC, a Delaware limited liability company and wholly owned subsidiary of HoldCo ("Faeth"), First Merger Sub merged with and into HoldCo, with HoldCo surviving the first merger as a wholly owned subsidiary of the Issuer, and immediately following the first merger, HoldCo merged with and into Second Merger Sub, with Second Merger Sub surviving the second merger as a wholly owned subsidiary of the Issuer (such mergers, the "Merger").
3. Footnote continued: Upon the closing of the Merger, shares of outstanding common stock of HoldCo were converted into the right to receive 44.763 shares of the Issuer's Series B Preferred Stock.
Remarks:
Exhibit 24 - Power of Attorney
/s/ Josiah Craver, Attorney-in-Fact 06/16/2026
** 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.
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ATTACHMENTS / EXHIBITS

ex24-06162026_080601.htm

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