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  4. [Form 4] Sensei Biotherapeutics, Inc. Insider Trading Activity

Sensei Biotherapeutics (SNSE) stake by Millennium entities hits 147,731 shares

Filing Impact
(Moderate)
Filing Sentiment
(Positive)
Form Type
4

Rhea-AI Filing Summary

Entities associated with Millennium Management LLC reported active trading in Sensei Biotherapeutics, Inc. common stock over March 31 and April 1, 2026. Across multiple open-market purchases and sales, they were net buyers of 9,439 shares, with 12,180 shares purchased and 2,741 shares sold. Following these transactions, Millennium Management LLC beneficially owned 147,731 shares of Sensei common stock indirectly. The trades were executed by ICS Opportunities II LLC or other trading entities under Millennium’s voting control, and each reporting person disclaims beneficial ownership beyond any pecuniary interest.

Positive

  • None.

Negative

  • None.

Insights

Millennium-linked entities were net buyers of Sensei stock while actively trading around their position.

Reporting entities tied to Millennium Management LLC executed a series of open-market trades in Sensei Biotherapeutics common stock on March 31 and April 1, 2026. They bought 12,180 shares and sold 2,741 shares, resulting in a net purchase of 9,439 shares and post-trade indirect beneficial ownership of 147,731 shares.

These are institutional trades made through ICS Opportunities II LLC and other entities under Millennium’s voting control. The filing states that each reporting person disclaims beneficial ownership beyond any pecuniary interest, which is common language for complex fund structures.

The mix of buys and sells, with a net-buy outcome, suggests position adjustment rather than a directional overhaul. There are no derivative positions reported in this filing, so the visible exposure is entirely in common stock. Subsequent filings would show whether this stake continues to grow or is trimmed further.

Insider MILLENNIUM MANAGEMENT LLC, ICS OPPORTUNITIES II LLC, MILLENNIUM GROUP MANAGEMENT LLC, ENGLANDER ISRAEL A
Role null | null | null | null
Bought 12,180 shs ($382K)
Sold 2,741 shs ($77K)
Type Security Shares Price Value
Purchase Common Stock 1,161 $31.5309 $37K
Purchase Common Stock 1,613 $34.5863 $56K
Purchase Common Stock 3,401 $35.4554 $121K
Sale Common Stock 1,104 $31.52 $35K
Sale Common Stock 46 $34.7464 $2K
Purchase Common Stock 616 $24.6857 $15K
Purchase Common Stock 1,770 $25.3209 $45K
Purchase Common Stock 1,048 $26.7259 $28K
Purchase Common Stock 17 $27.7838 $472.32
Purchase Common Stock 186 $30.4754 $6K
Purchase Common Stock 1,957 $31.4512 $62K
Purchase Common Stock 411 $32.5962 $13K
Sale Common Stock 191 $24.2843 $5K
Sale Common Stock 1,251 $25.1676 $31K
Sale Common Stock 57 $27.1147 $2K
Sale Common Stock 5 $28.405 $142.03
Sale Common Stock 87 $31.52 $3K
Holdings After Transaction: Common Stock — 147,731 shares (Indirect, See footnote)
Footnotes (1)
  1. Represents volume-weighted average price ("VWAP") of purchases of 616 shares of common stock ("Common Stock"), par value $0.0001 per share, of Sensei Biotherapeutics, Inc. (the "Company") on March 31, 2026 at prices ranging from $23.91 to $24.90. Upon request by the Commission staff, the Company, or a security holder of the Company, the reporting persons will provide full information regarding the number of shares purchased or sold by the reporting person at each separate price within each range represented by a VWAP disclosed herein. In each case, the number of shares of the Company's Common Stock disclosed in column 5 is the number of shares of the Company's Common Stock beneficially owned by Millennium Management LLC at the conclusion of the transactions on the date disclosed in the corresponding entry in column 2. The transactions in the Company's Common Stock reported herein were made by ICS Opportunities II LLC or other trading entities, in each case subject to voting control and investment discretion by Millennium Management LLC, Millennium Group Management LLC (the managing member of Millennium Management LLC) and Israel A. Englander (the sole voting trustee of the managing member of Millennium Group Management LLC). Each reporting person disclaims beneficial ownership of the shares of the Company's Common Stock disclosed herein except to the extent of such reporting person's pecuniary interest therein, if any. Represents VWAP of purchases of 1,770 shares of the Company's Common Stock on March 31, 2026 at prices ranging from $25.13 to $26.12. Represents VWAP of purchases of 1,048 shares of the Company's Common Stock on March 31, 2026 at prices ranging from $26.2587 to $27.1994. Represents VWAP of purchases of 17 shares of the Company's Common Stock on March 31, 2026 at prices ranging from $27.525 to $28.405. Represents VWAP of purchases of 186 shares of the Company's Common Stock on March 31, 2026 at prices ranging from $30.1693 to $30.73. Represents VWAP of purchases of 1,957 shares of the Company's Common Stock on March 31, 2026 at prices ranging from $31.215 to $31.17. Represents VWAP of purchases of 411 shares of the Company's Common Stock on March 31, 2026 at prices ranging from $32.4343 to $32.91. Represents VWAP of sales of 191 shares of the Company's Common Stock on March 31, 2026 at prices ranging from $23.91 to $24.6089. Represents VWAP of sales of 1,251 shares of the Company's Common Stock on March 31, 2026 at prices ranging from $25.13 to $25.45. Represents sales of 57 shares of the Company's Common Stock on March 31, 2026 at $27.1147 per share. Represents sales of 5 shares of the Company's Common Stock on March 31, 2026 at $28.4050 per share. Represents sales of 87 shares of the Company's Common Stock on March 31, 2026 at $31.52 per share. Represents VWAP of purchases of 1,161 shares of the Company's Common Stock on April 1, 2026 at prices ranging from $31.52 to $32.50. Represents VWAP of purchases of 1,613 shares of the Company's Common Stock on April 1, 2026 at prices ranging from $34.04 to $34.98. Represents VWAP of purchases of 3,401 shares of the Company's Common Stock on April 1, 2026 at prices ranging from $35.06 to $35.90. Represents sales of 1,104 shares of the Company's Common Stock on April 1, 2026 at $31.52 per share. Represents VWAP of sales of 46 shares of the Company's Common Stock on April 1, 2026 at prices ranging from $34.5271 to $35.3850.
Shares purchased 12,180 shares Open-market purchases of common stock across 2026-03-31 and 2026-04-01
Shares sold 2,741 shares Open-market sales of common stock across 2026-03-31 and 2026-04-01
Net shares bought 9,439 shares Net-buy direction from transaction summary
Post-trade holdings 147,731 shares Common stock beneficially owned by Millennium Management LLC after transactions
Largest single purchase 3,401 shares at $35.4554 Open-market purchase on 2026-04-01
Largest single sale 1,251 shares at $25.1676 Open-market sale on 2026-03-31
Number of buy transactions 10 purchases Non-derivative common stock transactions
Number of sell transactions 7 sales Non-derivative common stock transactions
volume-weighted average price ("VWAP") financial
"Represents volume-weighted average price ("VWAP") of purchases of 616 shares of common stock"
open-market purchase financial
"transaction_action": "open-market purchase""
An open-market purchase is when an investor or a company buys shares on a public stock exchange at the going market price, rather than through a private deal. It matters to investors because these purchases change how many shares are available, can push the stock price up or signal confidence from large buyers, and often affect per-share metrics like earnings—think of it like someone buying lots of apples off a grocery shelf, reducing supply and potentially raising the price.
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.
beneficial ownership financial
"disclaims beneficial ownership of the shares of the Company's Common Stock"
Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.
pecuniary interest financial
"except to the extent of such reporting person's pecuniary interest therein"
voting control and investment discretion financial
"subject to voting control and investment discretion by Millennium Management LLC"
Form 4 Insider Transactions: What Each Field Means →
SEC Form 4
FORM 4UNITED 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
X
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
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*
MILLENNIUM MANAGEMENT LLC
(Last)(First)(Middle)
399 PARK AVENUE
(Street)
NEW YORK NEW YORK 10022
(City)(State)(Zip)
UNITED STATES
(Country)		2. Issuer Name and Ticker or Trading Symbol
Sensei Biotherapeutics, Inc. [ SNSE ] 		5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
DirectorX10% Owner
Officer (give title below)Other (specify below)
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
03/31/2026		6. Individual or Joint/Group Filing (Check Applicable Line)
Form filed by One Reporting Person
XForm filed by More than One Reporting Person
4. If Amendment, Date of Original Filed (Month/Day/Year)

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)
CodeVAmount(A) or (D)Price
Common Stock03/31/2026P616A$24.6857(1)146,657(2)ISee footnote(3)
Common Stock03/31/2026P1,770A$25.3209(4)146,657(2)ISee footnote(3)
Common Stock03/31/2026P1,048A$26.7259(5)146,657(2)ISee footnote(3)
Common Stock03/31/2026P17A$27.7838(6)146,657(2)ISee footnote(3)
Common Stock03/31/2026P186A$30.4754(7)146,657(2)ISee footnote(3)
Common Stock03/31/2026P1,957A$31.4512(8)146,657(2)ISee footnote(3)
Common Stock03/31/2026P411A$32.5962(9)146,657(2)ISee footnote(3)
Common Stock03/31/2026S191D$24.2843(10)146,657(2)ISee footnote(3)
Common Stock03/31/2026S1,251D$25.1676(11)146,657(2)ISee footnote(3)
Common Stock03/31/2026S57D$27.1147(12)146,657(2)ISee footnote(3)
Common Stock03/31/2026S5D$28.405(13)146,657(2)ISee footnote(3)
Common Stock03/31/2026S87D$31.52(14)146,657(2)ISee footnote(3)
Common Stock04/01/2026P1,161A$31.5309(15)147,731(2)ISee footnote(3)
Common Stock04/01/2026P1,613A$34.5863(16)147,731(2)ISee footnote(3)
Common Stock04/01/2026P3,401A$35.4554(17)147,731(2)ISee footnote(3)
Common Stock04/01/2026S1,104D$31.52(18)147,731(2)ISee footnote(3)
Common Stock04/01/2026S46D$34.7464(19)147,731(2)ISee footnote(3)
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)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
1. Name and Address of Reporting Person*
MILLENNIUM MANAGEMENT LLC
(Last)(First)(Middle)
399 PARK AVENUE
(Street)
NEW YORK NEW YORK 10022
(City)(State)(Zip)
UNITED STATES
(Country)
Relationship of Reporting Person(s) to Issuer
DirectorX10% Owner
Officer (give title below)Other (specify below)
1. Name and Address of Reporting Person*
ICS OPPORTUNITIES II LLC
(Last)(First)(Middle)
C/O MILLENNIUM MANAGEMENT LLC
399 PARK AVENUE
(Street)
NEW YORK NEW YORK 10022
(City)(State)(Zip)
UNITED STATES
(Country)
Relationship of Reporting Person(s) to Issuer
DirectorX10% Owner
Officer (give title below)Other (specify below)
1. Name and Address of Reporting Person*
MILLENNIUM GROUP MANAGEMENT LLC
(Last)(First)(Middle)
399 PARK AVENUE
(Street)
NEW YORK NEW YORK 10022
(City)(State)(Zip)
UNITED STATES
(Country)
Relationship of Reporting Person(s) to Issuer
DirectorX10% Owner
Officer (give title below)Other (specify below)
1. Name and Address of Reporting Person*
ENGLANDER ISRAEL A
(Last)(First)(Middle)
C/O MILLENNIUM MANAGEMENT LLC
399 PARK AVENUE
(Street)
NEW YORK NEW YORK 10022
(City)(State)(Zip)
UNITED STATES
(Country)
Relationship of Reporting Person(s) to Issuer
DirectorX10% Owner
Officer (give title below)Other (specify below)
Explanation of Responses:
1. Represents volume-weighted average price ("VWAP") of purchases of 616 shares of common stock ("Common Stock"), par value $0.0001 per share, of Sensei Biotherapeutics, Inc. (the "Company") on March 31, 2026 at prices ranging from $23.91 to $24.90. Upon request by the Commission staff, the Company, or a security holder of the Company, the reporting persons will provide full information regarding the number of shares purchased or sold by the reporting person at each separate price within each range represented by a VWAP disclosed herein.
2. In each case, the number of shares of the Company's Common Stock disclosed in column 5 is the number of shares of the Company's Common Stock beneficially owned by Millennium Management LLC at the conclusion of the transactions on the date disclosed in the corresponding entry in column 2.
3. The transactions in the Company's Common Stock reported herein were made by ICS Opportunities II LLC or other trading entities, in each case subject to voting control and investment discretion by Millennium Management LLC, Millennium Group Management LLC (the managing member of Millennium Management LLC) and Israel A. Englander (the sole voting trustee of the managing member of Millennium Group Management LLC). Each reporting person disclaims beneficial ownership of the shares of the Company's Common Stock disclosed herein except to the extent of such reporting person's pecuniary interest therein, if any.
4. Represents VWAP of purchases of 1,770 shares of the Company's Common Stock on March 31, 2026 at prices ranging from $25.13 to $26.12.
5. Represents VWAP of purchases of 1,048 shares of the Company's Common Stock on March 31, 2026 at prices ranging from $26.2587 to $27.1994.
6. Represents VWAP of purchases of 17 shares of the Company's Common Stock on March 31, 2026 at prices ranging from $27.525 to $28.405.
7. Represents VWAP of purchases of 186 shares of the Company's Common Stock on March 31, 2026 at prices ranging from $30.1693 to $30.73.
8. Represents VWAP of purchases of 1,957 shares of the Company's Common Stock on March 31, 2026 at prices ranging from $31.215 to $31.17.
9. Represents VWAP of purchases of 411 shares of the Company's Common Stock on March 31, 2026 at prices ranging from $32.4343 to $32.91.
10. Represents VWAP of sales of 191 shares of the Company's Common Stock on March 31, 2026 at prices ranging from $23.91 to $24.6089.
11. Represents VWAP of sales of 1,251 shares of the Company's Common Stock on March 31, 2026 at prices ranging from $25.13 to $25.45.
12. Represents sales of 57 shares of the Company's Common Stock on March 31, 2026 at $27.1147 per share.
13. Represents sales of 5 shares of the Company's Common Stock on March 31, 2026 at $28.4050 per share.
14. Represents sales of 87 shares of the Company's Common Stock on March 31, 2026 at $31.52 per share.
15. Represents VWAP of purchases of 1,161 shares of the Company's Common Stock on April 1, 2026 at prices ranging from $31.52 to $32.50.
16. Represents VWAP of purchases of 1,613 shares of the Company's Common Stock on April 1, 2026 at prices ranging from $34.04 to $34.98.
17. Represents VWAP of purchases of 3,401 shares of the Company's Common Stock on April 1, 2026 at prices ranging from $35.06 to $35.90.
18. Represents sales of 1,104 shares of the Company's Common Stock on April 1, 2026 at $31.52 per share.
19. Represents VWAP of sales of 46 shares of the Company's Common Stock on April 1, 2026 at prices ranging from $34.5271 to $35.3850.
Remarks:
Assuming, without conceding, the application of Section 16(b) of the Securities Exchange Act of 1934, the reporting persons have disgorged to the Company all amounts that could be deemed profit realized by them from the transactions in the Company's Common Stock reported on this Form 4 and the other two statements on Form 4 filed by Millennium Management LLC on the same date.
MILLENNIUM MANAGEMENT LLC: By: /s/ Gil Raviv, Global General Counsel05/14/2026
ICS OPPORTUNITIES II LLC, By: Millennium Management LLC, its Investment Manager: By: /s/ Gil Raviv, Global General Counsel05/14/2026
MILLENNIUM GROUP MANAGEMENT LLC: By: /s/ Gil Raviv, Global General Counsel05/14/2026
/s/ Israel A. Englander05/14/2026
** Signature of Reporting PersonDate
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)

Source: View Original Filing on SEC EDGAR

FAQ

How many Sensei Biotherapeutics (SNSE) shares do the reporting entities hold after these trades?

After the reported trades, Millennium Management LLC beneficially owned 147,731 shares of Sensei Biotherapeutics common stock indirectly. This figure reflects holdings at the conclusion of the disclosed transactions on the respective trade dates reported in the filing.

Were the SNSE insider transactions open-market buys or sales?

The filing shows both open-market purchases and open-market sales of Sensei Biotherapeutics common stock. Overall, the reporting entities bought 12,180 shares and sold 2,741 shares, resulting in a net-buy position change of 9,439 shares across the two trading days.

Who actually executed the SNSE trades reported for Millennium Management LLC?

The trades were executed by ICS Opportunities II LLC or other trading entities. These entities are subject to voting control and investment discretion by Millennium Management LLC, Millennium Group Management LLC, and Israel A. Englander, according to the filing’s footnote disclosures.