Sensei Biotherapeutics details Series B conversion impact

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.

Rhea-AI Filing Summary

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.

8-K Event Classification

2 items: 8.01, 9.01

2 items

Item 8.01 Other Events Other

Voluntary disclosure of events the company deems important to shareholders but not covered by other items.

Item 9.01 Financial Statements and Exhibits Exhibits

Financial statements, pro forma financial information, or exhibit attachments filed with this report.

Key Figures

Cash and cash equivalents: $152,325 thousand Marketable securities: $50,468 thousand Total assets: $205,381 thousand +5 more

8 metrics

Cash and cash equivalents $152,325 thousand Balance sheet as of March 31, 2026

Marketable securities $50,468 thousand Balance sheet as of March 31, 2026

Total assets $205,381 thousand Balance sheet as of March 31, 2026

Series B redeemable convertible preferred stock $328,476 thousand Pre-conversion carrying amount as of March 31, 2026

Total stockholders’ equity pro forma $184,570 thousand Pro forma balance sheet after conversion adjustments

Net loss $170,236 thousand Three months ended March 31, 2026

Acquired in-process R&D expense $132,957 thousand Three months ended March 31, 2026

PIPE gross proceeds $200.0 million Financing concurrent with Faeth acquisition on February 2026

Key Terms

Series B Non-Voting Convertible Preferred Stock, unaudited pro forma condensed financial information, PIPE Securities, beneficial ownership limitations, +2 more

6 terms

Series B Non-Voting Convertible Preferred Stock financial

"issuance of shares of common stock ... upon conversion of Series B Non-Voting Convertible Preferred Stock"

A Series B non-voting convertible preferred stock is a class of company shares that gives holders financial priority—such as fixed dividends and first claim on assets if the company is sold—while not granting voting rights. It can be converted into regular common shares under set conditions, which matters to investors because conversion can increase upside participation but also dilute existing owners; the preference reduces downside risk like a safety buffer.

unaudited pro forma condensed financial information financial

"the Company is filing unaudited pro forma condensed consolidated financial information of the Company"

PIPE Securities financial

"investors were issued an aggregate of 14,440.395 shares of Series B Preferred Stock ... (the “PIPE Securities”)"

beneficial ownership limitations financial

"on an as-converted-to-common basis and without giving effect to any beneficial ownership limitations"

Beneficial ownership limitations are rules or contractual caps that restrict how much of a company’s stock an individual or entity can be treated as owning or controlling for legal, regulatory or corporate-governance purposes. They matter to investors because such limits affect voting power, reporting obligations, takeover risk and the ability to increase a stake — like an elevator weight limit or a lane divider that prevents any one car from taking over the whole road.

Parent Stockholder Matters financial

"Subject to the receipt of stockholder approval of the Parent Stockholder Matters (as defined in the Merger Agreement)"

acquired in-process research and development financial

"Acquired in-process research and development | | | 132,957"

Acquired in-process research and development is the unfinished scientific work and product programs a company buys from another firm as part of a deal — think of it as buying an unfinished prototype and the team working on it. Investors care because the buyer is paying for future potential that may never materialize; that payment often shows up as a large one-time cost and signals higher risk and reward tied to future products rather than current sales.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What is Sensei Biotherapeutics (SNSE) asking shareholders to approve at the 2026 annual meeting?

Sensei Biotherapeutics is asking shareholders to approve issuing common stock upon conversion of Series B Non-Voting Convertible Preferred Stock. The conversion will exceed 20% of outstanding common shares and cause a change of control under Nasdaq Listing Rules 5635(a) and 5635(b).

How much capital did Sensei Biotherapeutics (SNSE) raise in the February 2026 PIPE financing?

Sensei Biotherapeutics raised $200.0 million of gross proceeds in a February 2026 PIPE financing. Investors received 14,440.395 shares of Series B preferred stock, equal to 14,440,395 common shares on an as-converted basis, priced at $13,850 per preferred share, or $13.85 per common-equivalent share.

What did Sensei Biotherapeutics (SNSE) pay to acquire Faeth Therapeutics?

To acquire Faeth Therapeutics, Sensei Biotherapeutics issued 10,497.098 shares of Series B Non-Voting Convertible Preferred Stock. These preferred shares represent 10,497,098 shares of common stock on an as-converted basis, excluding any beneficial ownership limitations agreed with individual holders.

What is the purpose of Sensei Biotherapeutics’ (SNSE) unaudited pro forma financial information?

The unaudited pro forma financial information shows how Sensei Biotherapeutics’ balance sheet and results would look after converting Series B preferred stock into common stock. It illustrates the impact of the planned conversion but may differ from the company’s actual post-conversion financial condition.

What were Sensei Biotherapeutics’ (SNSE) key financial figures as of March 31, 2026?

As of March 31, 2026, Sensei Biotherapeutics reported total assets of $205.4 million, including $152.3 million in cash and cash equivalents and $50.5 million in marketable securities. For the quarter, it recorded a net loss of $170.2 million and total operating expenses of $170.6 million.

How will the Series B preferred stock of Sensei Biotherapeutics (SNSE) convert into common shares?

Each share of Sensei Biotherapeutics’ Series B Non-Voting Convertible Preferred Stock automatically converts into 1,000 shares of common stock after stockholders approve specified matters. The conversion is subject to individual beneficial ownership limitations set for each holder in the merger and financing agreements.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 05/21/2026 - 05:12 PM EDT Learn about SEC filing dates

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): May 21, 2026

Sensei Biotherapeutics, Inc.

(Exact Name of Registrant as Specified in its Charter)

Delaware		001-39980		83-1863385
(State or Other Jurisdiction of Incorporation)		(Commission File Number)		(IRS Employer Identification No.)
1405 Research Blvd, Suite 125
Rockville, MD				20850
(Address of Principal Executive Offices)				(Zip Code)
451 D Street, Suite 710
Boston, MA				02210
(Former Address of Principal Executive Offices)				(Zip Code)

Registrant’s telephone number, including area code: (240) 243-8000

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Securities Exchange Act of 1934:

Title of each class		Trading symbol		Name of each exchange on which registered
Common Stock		SNSE		The Nasdaq Stock Market LLC

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 8.01. Other Events.

As previously announced, Sensei Biotherapeutics, Inc. (the “Company”) will hold its 2026 annual meeting of stockholders (“Annual Meeting”) of the Company on June 10, 2026, at 11:00 a.m. Eastern Daylight Time, unless postponed or adjourned to a later date. At the Annual Meeting, stockholders will be asked to approve, among other things, the issuance of shares of common stock, par value $0.0001 per share (“common stock”), of the Company upon conversion of Series B Non-Voting Convertible Preferred Stock, par value $0.0001 per shares (“Series B Preferred Stock”), which will (a) represent more than 20% of the shares of common stock outstanding and (b) result in the change of control of the Company pursuant to Nasdaq Listing Rules 5635(a) and 5635(b), respectively. In connection with the Annual Meeting, the Company is filing unaudited pro forma condensed consolidated financial information of the Company for the quarter ended March 31, 2026, presenting the historical consolidated financial position of the Company for the quarter ended March 31, 2026, adjusted to give effect to the conversion of the shares of Series B Preferred Stock into shares of common stock.

The unaudited pro forma condensed financial information, including the notes thereto, should be read in conjunction with the financial statements of the Company and the Company’s management’s discussion and analysis of financial condition and results of operations included in the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2026, filed with the Securities and Exchange Commission (“SEC”) on May 15, 2026. Such unaudited pro forma condensed financial information is presented for illustrative purposes only and may not be an indication of the Company’s financial condition following the conversion of the Series B Preferred Stock for several reasons. The unaudited pro forma condensed financial information has been derived from the historical unaudited financial statements of the Company for the quarter ended March 31, 2026, and certain adjustments and assumptions have been made regarding the Company after giving effect to the conversion of the Series B Preferred Stock. The information upon which these adjustments and assumptions have been made is preliminary, and these kinds of adjustments and assumptions are difficult to make with accuracy. Moreover, the unaudited pro forma condensed financial information does not reflect all costs that are expected to be incurred by the Company in connection with the conversion of the Series B Preferred Stock. As a result, the actual financial condition of the Company following the conversion of the Series B Preferred Stock may not be consistent with, or evident from, the unaudited pro forma condensed financial information. The assumptions used in preparing the unaudited pro forma condensed financial information may not prove to be accurate, and other factors may affect the Company’s financial condition following the conversion of the Series B Preferred Stock. For more information, please see Exhibit 99.1 attached hereto and incorporated herein by reference.

For more information regarding the Annual Meeting, please refer to the Company’s Definitive Proxy Statement, filed with the SEC on April 27, 2026.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

Exhibit Number		Exhibit Description
99.1		Unaudited Pro Forma Condensed Financial Information of Sensei Biotherapeutics, Inc. for the quarter ended March 31, 2026.
104		The cover page from this Current Report on Form 8-K, formatted in Inline XBRL

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

						Sensei Biotherapeutics, Inc.
Date: May 21, 2026						/s/ Christopher W. Gerry
						Christopher W. Gerry
						President and General Counsel

Exhibit 99.1

SENSEI BIOTHERAPEUTICS, INC.

UNAUDITED PRO FORMA CONDENSED FINANCIAL INFORMATION

On February 17, 2026, Sensei Biotherapeutics, Inc. (the “Company”) acquired Faeth Holdings Therapeutics, Inc. (“Faeth HoldCo”) and its wholly owned subsidiary Faeth Therapeutics, LLC (“Faeth Subsidiary” and, together with Faeth HoldCo, “Faeth Therapeutics” or “Faeth”) pursuant to an Agreement and Plan of Merger (the “Merger Agreement”), dated as of February 17, 2026, by and among the Company, its merger subsidiaries, Faeth HoldCo and Faeth Subsidiary (such transaction, the “Acquisition”).

Under the terms of the Merger Agreement, the Company issued to the stockholders of Faeth an aggregate of 10,497.0980 shares of Series B Non-Voting Convertible Preferred Stock, par value $0.0001 per share (the “Series B Preferred Stock”), representing 10,497,098 shares of common stock of the Company, par value $0.0001 per share (“Common Stock”), on an as-converted-to-common basis and without giving effect to any beneficial ownership limitations.

Concurrently with the acquisition of Faeth Therapeutics, on February 17, 2026, the Company entered into a Securities Purchase Agreement (the “Purchase Agreement”) with new and returning investors to raise $200.0 million of gross proceeds in which investors were issued an aggregate of 14,440.395 shares of Series B Preferred Stock, or 14,440,395 on an as-converted-to-common basis and without giving effect to any beneficial ownership limitations, (the “PIPE Securities”) at a price of $13,850 per share, or $13.85 per share on an as-converted-to-common basis, (collectively, the “Financing”). The Financing closed on February 20, 2026.

Subject to the receipt of stockholder approval of the Parent Stockholder Matters (as defined in the Merger Agreement), each share of Series B Preferred Stock will automatically convert into 1,000 shares of Common Stock, subject to certain beneficial ownership limitations established by each holder.

The following unaudited pro forma condensed financial information presents the historical consolidated financial position and results of operations of the Company, adjusted to give effect to the conversion of the Series B Preferred Stock into common stock (the “Conversion”) that will automatically occur three business days subsequent to the expected affirmative vote for stockholder approval of the Parent Stockholder Matters. The vote for stockholder approval of the Parent Stockholder Matters is scheduled to occur on June 10, 2026. The unaudited pro forma condensed balance sheet gives pro forma effect to the Conversion as if it had been consummated on March 31, 2026. The unaudited pro forma condensed statement of operations for the three months ended March 31, 2026 gives effect to the Conversion as if it had occurred on January 1, 2026.

The unaudited pro forma condensed financial information is based on the assumptions and adjustments described in the accompanying notes. Accordingly, the pro forma adjustments are preliminary, subject to further revision as additional information becomes available and additional analyses are performed and have been made solely for the purpose of providing unaudited pro forma condensed financial information.

The unaudited pro forma condensed financial information, including the notes thereto, should be read in conjunction with the financial statements of the Company and the Company’s management’s discussion and analysis of financial condition and results of operations included in the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2026, filed with the Securities and Exchange Commission (“SEC”) on May 15, 2026.

UNAUDITED PRO FORMA CONDENSED BALANCE SHEET

AS OF MARCH 31, 2026

(in thousands)

						Transaction Accounting Adjustments
		March 31, 2026				Conversion				Note References				Pro Forma As Adjusted
Assets
Current assets:
Cash and cash equivalents		$	152,325			$	—							$	152,325
Marketable securities			50,468												50,468
Prepaid expenses			974												974
Other current assets			465												465
Total current assets			204,232				—								204,232
Right-of-use assets - operating leases, net			913												913
Right-of-use assets - financing leases, net			—												—
Property and equipment, net			69												69
Other non-current assets			167												167
Total assets		$	205,381			$	—							$	205,381
Liabilities, redeemable convertible preferred stock and stockholders’ (deficit) equity
Current liabilities:
Accounts payable and accrued expenses		$	8,982			$	—							$	8,982
Compensation and employee benefits liabilities			4,169												4,169
Operating lease liabilities, current			1,021												1,021
Financing lease liabilities, current			18												18
Total current liabilities			14,190				—								14,190
Operating lease liabilities, non-current			—												—
Other non-current liabilities			1				—								1
Total liabilities			14,191				—								14,191
Commitments and contingencies
Series B redeemable convertible preferred stock			328,476				(321,856	)			A				6,620
Stockholders’ (deficit) equity:
Common stock			—				2				A				2
Additional paid-in capital			316,111				321,854				A				637,965
Accumulated deficit			(453,373	)											(453,373	)
Accumulated other comprehensive (loss) income			(24	)											(24	)
Total stockholders’ (deficit) equity			(137,286	)			321,856								184,570
Total liabilities, redeemable convertible preferred stock, and stockholders’ (deficit) equity		$	205,381			$	—							$	205,381

UNAUDITED PRO FORMA CONDENSED STATEMENT OF OPERATIONS

FOR THE THREE MONTHS ENDED MARCH 31, 2026

(in thousands, except share and per share amounts)

		For the Three Months Ended March 31, 2026
						Transaction Accounting Adjustments
		Actual				Conversion				Note References				Pro Forma As Adjusted
Operating expenses:
Research and development		$	17,957			$	—							$	17,957
General and administrative			19,713												19,713
Acquired in-process research and development			132,957												132,957
Total operating expenses			170,627												170,627
Loss from operations			(170,627)												(170,627)
Other income (expense), net:
Interest income, net			392												392
Other (expense) income, net			(1)												(1)
Net loss		$	(170,236)			$	—							$	(170,236)
Net loss per common share, basic and diluted		$	(131.45)											$	(6.62)
Weighted-average shares outstanding, basic and diluted			1,295,052				24,434,920				A				25,729,972
Comprehensive loss:
Net loss		$	(170,236)			$	—							$	(170,236)
Other comprehensive items:
Unrealized (loss) gain on marketable securities			(25)												(25)
Total other comprehensive (loss) income			(25	)											(25	)
Total comprehensive loss		$	(170,261)			$	—							$	(170,261)

SENSEI BIOTHERAPEUTICS, INC.

NOTES TO UNAUDITED PRO FORMA CONDENSED BALANCE SHEET

Note 1. Transaction accounting adjustments for the Conversion

A. Reflects the expected conversion of 24,434.92 shares of Series B Preferred Stock into 24,434,920 shares of common stock that will automatically occur three business days subsequent to the expected affirmative vote for the Conversion. The aforementioned vote is scheduled to occur on June 10, 2026. The transaction accounting adjustments reflecting the Conversion do not reflect the conversion of shares of Series B Preferred Stock that are not expected to convert due to certain beneficial ownership limitations established by each holder based solely on the shares of Series B Preferred Stock beneficially owned by the holders thereof. The number of shares of Series B Preferred Stock that ultimately convert into shares of common stock may be more or less than our expectations.

Filing Exhibits & Attachments

5 documents

Press Releases

• EX-99.1 EX-99.1 77.8 KB

Other Documents

• EX-101 XBRL TAXONOMY EXTENSION SCHEMA 3.1 KB
• EX-101 XBRL TAXONOMY EXTENSION DEFINITION LINKBASE 13.4 KB
• EX-101 XBRL TAXONOMY EXTENSION LABEL LINKBASE 22.0 KB
• EX-101 XBRL TAXONOMY EXTENSION PRESENTATION LINKBASE 14.2 KB