Sensei Biotherapeutics, Inc. SEC Filings

Sensei Biotherapeutics, Inc. held its 2026 annual stockholder meeting, where stockholders approved several significant capital and compensation measures. They authorized an increase in the company’s common stock authorization from 12,500,000 to 300,000,000 shares, greatly expanding capacity for future issuances. Stockholders also approved the issuance of common shares upon conversion of Series B Non-Voting Convertible Preferred Stock, which will represent more than 20% of outstanding common stock and result in a change of control under Nasdaq Listing Rules 5635(a) and 5635(b). In addition, investors approved a new 2026 Equity Incentive Plan with an initial reserve of 2,671,981 shares plus recycling of up to 311,164 additional shares, and a 2026 Employee Stock Purchase Plan with an initial reserve of 267,198 shares, each with automatic annual share increases through 2036. All director nominees were elected, the company’s auditor was ratified, and quorum was strong, with 1,077,174 shares (80.32% of 1,341,140 shares outstanding as of the record date) represented.

Sensei Biotherapeutics, Inc. ownership filing shows a coordinated filing by ICS Opportunities II LLC, Millennium Management LLC, Millennium Group Management LLC and Israel A. Englander reporting 41,561 shares, representing 3.1% of Common Stock (CUSIP 81728A207) as disclosed on the cover pages. The filing states the holdings reflect shared voting and dispositive power of 41,561 shares among the reporting parties and attaches a Joint Filing Agreement dated 06/02/2026.

The filing clarifies the shares are held by entities subject to voting control and investment discretion by Millennium Management LLC and related managers; the parties note this should not be construed as an admission of beneficial ownership. Signatures are dated 06/02/2026.

Sensei Biotherapeutics filed Amendment No. 1 to its annual report to replace the Business section in response to SEC staff comments. The amendment updates the description of the company following its February 2026 acquisition of Faeth Therapeutics.

The combined company is now a clinical-stage oncology business centered on PIKTOR, an oral multi-node inhibitor of the PI3K/AKT/mTOR pathway being studied in a Phase 2 trial for second-line advanced endometrial cancer, with topline data expected by year-end 2026, and in a Phase 1b trial for HR+/HER2- advanced breast cancer. In connection with the Faeth acquisition, Sensei received $200 million in gross proceeds from a 2026 private placement to advance PIKTOR.

As of June 30, 2025, non-affiliate common equity market value was about $7.1 million based on an $8.58 share price, and 1,340,281 common shares were outstanding as of March 23, 2026. The amendment also refreshes executive certifications without changing previously reported financial statements.

Sensei Biotherapeutics, Inc. is registering 24,868,028 shares of Common Stock for resale by selling stockholders under a shelf prospectus. The Resale Shares include 10,425,531 Merger Conversion Shares, 14,440,395 Private Placement Conversion Shares and 2,102 Warrant Conversion Shares. Conversion of the Series B Preferred Stock into Common Stock occurs at 1,000 shares per Series B share, but conversion and resale are subject to stockholder approvals described as the Conversion Proposal and the Authorized Share Proposal and to beneficial ownership limits set by preferred holders. The company will not receive proceeds from sales by the selling stockholders; the 2026 Private Placement raised approximately $200 million at $13,850 per Series B Preferred share. If approved by Nasdaq and stockholders, the company expects to change its name to Faeth Therapeutics, Inc. and list under the symbol FTH. The last reported sale price for Common Stock was $21.14 on May 31, 2026.

Cambrian BioPharma Inc, a ten percent owner of Sensei Biotherapeutics, Inc., reported open-market sales of a total of 25,000 shares of Sensei common stock. The trades on June 1, 2026 were executed at prices ranging from $20.00 to $21.00 per share, based on a weighted average price disclosure.

Sensei Biotherapeutics, Inc. ten percent owner James Peyer reported open-market sales of 25,000 shares of Common Stock. The sales occurred on June 1, 2026 in two transactions: 24,524 shares at $20.00 per share and 476 shares at $21.14 per share.

After these transactions, he continued to hold more than 130,000 shares of Common Stock directly. A footnote explains that one reported price reflects a weighted average for trades executed in a range from $20.00 to $21.00, with detailed breakdowns available upon request.

Sensei Biotherapeutics updated its plans for reconstituting its board of directors around the 2026 Annual Meeting of Stockholders scheduled for June 10, 2026. Due to personal reasons, the planned appointment of Karen Vousden, Ph.D. to the board will be delayed, with the board intending to consider her appointment in the third or fourth quarter of 2026.

If the Required Company Stockholder Matters are approved at the Annual Meeting, the board plans to appoint Bob Holmen as chair of the Nominating and Corporate Governance Committee effective June 12, 2026, when other described appointments would take effect. The board has also approved a board size of five directors as of that date.

Sensei Biotherapeutics, Inc. is providing investors with unaudited pro forma financial statements showing the impact of converting its Series B Non-Voting Convertible Preferred Stock into common stock. This conversion, which requires stockholder approval, will represent more than 20% of outstanding common shares and result in a change of control under Nasdaq rules.

The company had total assets of $205.4 million as of March 31, 2026, including $152.3 million of cash and cash equivalents and $50.5 million of marketable securities. For the quarter, Sensei reported a net loss of $170.2 million, driven largely by $133.0 million of acquired in-process research and development.

In February 2026, Sensei acquired Faeth Therapeutics and issued 10,497.098 shares of Series B preferred stock, equivalent to 10,497,098 common shares on an as-converted basis, as part of the consideration. Concurrently, it raised $200.0 million of gross proceeds in a PIPE financing by issuing 14,440.395 Series B preferred shares, equivalent to 14,440,395 common shares, at $13,850 per preferred share, or $13.85 per share on an as-converted basis.

Sensei Biotherapeutics, Inc. reported that entities associated with Millennium Management LLC actively traded its Common Stock over several days in early April 2026. The trades were made by ICS Opportunities II LLC and other trading entities, with voting control and investment discretion held by Millennium Management LLC, Millennium Group Management LLC and Israel A. Englander.

Across these open-market transactions, the reporting entities sold 17,076 shares and purchased 4,215 shares of Common Stock at prices generally between $28.9417 and $35.5472 per share, resulting in a net sale. After the final transaction, Millennium Management LLC beneficially owned 133,986 shares indirectly, as disclosed in column 5. Each reporting person disclaims beneficial ownership beyond any pecuniary interest.