Bicara Therapeutics (BCAX) stake reaches 11.5% at RA Capital group

Rhea-AI Filing Summary

RA Capital Management and affiliates report a significant ownership position in Bicara Therapeutics Inc. common stock. The reporting group, including RA Capital Management, L.P., Peter Kolchinsky, Rajeev Shah, and RA Capital Healthcare Fund, L.P., reports beneficial ownership of 7,279,739 shares, representing 11.5% of Bicara’s common stock.

The Fund directly holds 4,603,418 shares, or 7.3% of the class. On February 26, 2026, the Fund bought 300,000 shares at $16.00 per share and 2,200,000 pre-funded warrants at $15.9999 each in Bicara’s February 2026 offering, for a total of $39,999,780 funded from its working capital.

The pre-funded warrants give the Fund the right to acquire 2,200,000 shares but include a 9.99% beneficial ownership blocker, so they cannot be exercised if doing so would push the Fund and its affiliates above that ownership threshold. Ownership percentages are based on 54,781,950 shares outstanding as of November 5, 2025 plus 8,581,250 shares issued in the February 2026 offering, and include certain exercisable stock options.

Insights

Equity ownership analyst

RA Capital discloses an 11.5% Bicara stake, including new offering purchases.

RA Capital and related entities now report beneficial ownership of 7,279,739 Bicara Therapeutics shares, or 11.5% of the company’s common stock. This includes 4,603,418 shares held by the RA Capital Healthcare Fund, which on February 26, 2026 participated in a Bicara public offering.

In that deal, the Fund purchased 300,000 shares at $16.00 per share and 2,200,000 pre-funded warrants at $15.9999 each, for a total of $39,999,780 funded from its working capital. The position calculation relies on 54,781,950 shares outstanding as of November 5, 2025 plus 8,581,250 newly issued shares from the February 2026 offering.

The pre-funded warrants allow acquisition of 2,200,000 additional shares but contain a 9.99% beneficial ownership blocker, which currently prevents exercise if it would move the Fund and affiliates above that level. Future company filings may clarify any later changes in RA Capital’s ownership or warrant exercise status.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 1)

BICARA THERAPEUTICS INC.

(Name of Issuer)

Common Stock, par value $0.0001 per share

(Title of Class of Securities)

Peter Kolchinsky
RA Capital Management, L.P., 200 Berkeley Street, 18th Floor
Boston, MA, 02116
617.778.2500

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

02/26/2026

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

SCHEDULE 13D

CUSIP Number(s):

1

Name of reporting person

RA Capital Management, L.P.

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 7,279,739.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 7,279,739.00

11

Aggregate amount beneficially owned by each reporting person

7,279,739.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

11.5 %

14

Type of Reporting Person (See Instructions)

IA, PN

SCHEDULE 13D

CUSIP Number(s):

1

Name of reporting person

Peter Kolchinsky

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 7,279,739.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 7,279,739.00

11

Aggregate amount beneficially owned by each reporting person

7,279,739.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

11.5 %

14

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13D

CUSIP Number(s):

1

Name of reporting person

Rajeev Shah

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF, OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 7,279,739.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 7,279,739.00

11

Aggregate amount beneficially owned by each reporting person

7,279,739.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

11.5 %

14

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13D

CUSIP Number(s):

1

Name of reporting person

RA Capital Healthcare Fund, L.P.

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

WC

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 4,603,418.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 4,603,418.00

11

Aggregate amount beneficially owned by each reporting person

4,603,418.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

7.3 %

14

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Stock, par value $0.0001 per share
(b)	Name of Issuer: BICARA THERAPEUTICS INC.
(c)	Address of Issuer's Principal Executive Offices: 116 Huntington Avenue, Suite 703, Boston, MASSACHUSETTS , 02116.
Item 1 Comment: This Amendment No. 1 (this "Amendment No. 1" or this "Schedule 13D/A") amends and supplements the statement on Schedule 13D originally filed with the Securities and Exchange Commission (the "SEC") on September 23, 2024 (the "Statement") by the Reporting Persons. Unless otherwise defined herein, capitalized terms used in this Amendment No. 1 shall have the meanings ascribed to them in the Statement. Unless amended or supplemented below, the information in the Statement remains unchanged.
Item 2.	Identity and Background
(a)	This Schedule 13D/A is being filed on behalf of RA Capital Management, L.P. ("RA Capital"), Peter Kolchinsky, Rajeev Shah, and RA Capital Healthcare Fund, L.P. (the "Fund"), who are collectively referred to herein as the "Reporting Persons." The agreement among the Reporting Persons to file this Schedule 13D/A jointly in accordance with Rule 13d-1(k) of the Securities Exchange Act of 1934, as amended (the "Act"), is attached hereto as Exhibit 99.1. The Reporting Persons' ownership of the Issuer's securities includes (i) 4,603,418 shares of common stock held directly by the Fund; (ii) 2,652,575 shares of common stock held by RA Capital Nexus Fund III, L.P. (the "Nexus Fund III"); and (iii) a total of 23,746 shares of common stock underlying vested stock options (right to buy) held by Jake Simson for the benefit of RA Capital. The Fund also holds Pre-Funded Warrants (as defined below) through which it has a right to acquire 2,200,000 shares of common stock. The Pre-Funded Warrants contain a provision (the "Beneficial Ownership Blocker") which precludes exercise of the warrants to the extent that, following exercise, the Fund, together with its affiliates and other attribution parties, would own more than 9.99% of the common stock outstanding. The Reporting Persons are currently prohibited from exercising the Pre-Funded Warrants. RA Capital Healthcare Fund GP, LLC is the general partner of the Fund and RA Capital Nexus Fund III GP, LLC is the general partner of the Nexus Fund III. The general partner of RA Capital is RA Capital Management GP, LLC, of which Dr. Kolchinsky and Mr. Shah are the controlling persons. RA Capital serves as investment adviser for the Fund and the Nexus Fund III and may be deemed a beneficial owner, for purposes of Section 13(d) of the Securities Exchange Act of 1934 (the "Act"), of any securities of the Issuer held by the Fund or the Nexus Fund III. The Fund and the Nexus Fund III have delegated to RA Capital the sole power to vote and the sole power to dispose of all securities held in the Fund's and the Nexus Fund III's portfolio, including the shares of the Issuer's common stock reported herein. Because the Fund and the Nexus Fund III have divested themselves of voting and investment power over the reported securities they hold and may not revoke that delegation on less than 61 days' notice, the Fund and the Nexus Fund III disclaim beneficial ownership of the securities they hold for purposes of Section 13(d) of the Act and therefore disclaim any obligation to report ownership of the reported securities under Section 13(d) of the Act. As managers of RA Capital, Dr. Kolchinsky and Mr. Shah may be deemed beneficial owners, for purposes of Section 13(d) of the Act, of any securities of the Issuer beneficially owned by RA Capital. RA Capital, Dr. Kolchinsky, and Mr. Shah disclaim beneficial ownership of the securities reported in this Schedule 13D/A other than for the purpose of determining their obligations under Section 13(d) of the Act, and the filing of this Schedule 13D/A shall not be deemed an admission that either RA Capital, Dr. Kolchinsky, or Mr. Shah is the beneficial owner of such securities for any other purpose.
(b)	The address of the principal business office of each of the Reporting Persons is 200 Berkeley Street, 18th Floor, Boston, MA 02116.
(c)	The Fund is a private investment vehicle. RA Capital provides investment management services to the Fund and the Nexus Fund III. The principal occupation of Dr. Kolchinsky and Mr. Shah is investment management.
(d)	During the last five years, none of the Reporting Persons has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors).
(e)	During the last five years, none of the Reporting Persons has been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree of final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.
(f)	See Item 6 of the cover pages.
Item 3.	Source and Amount of Funds or Other Consideration
	Item 3 of the Statement is hereby amended and supplemented as follows: On February 26, 2026, the Fund purchased (i) 300,000 shares of common stock at a price of $16.00 per share and (ii) 2,200,000 warrants (the "Pre-Funded Warrants") in lieu of shares of common stock, at a purchase price of $15.9999 per Pre-Funded Warrant, from the underwriters of the Issuer's public offering (the "February 2026 Offering"). The aggregate purchase price for all securities acquired by the Fund in the February 2026 Offering was $39,999,780, which was funded by the working capital of the Fund.
Item 5.	Interest in Securities of the Issuer
(a)	Rows 11 and 13 of each Reporting Person's cover page to this Schedule 13D/A set forth the aggregate number of shares of common stock and percentages of the shares of common stock beneficially owned by such Reporting Person and are incorporated by reference. The percentage set forth in each row 13 is based upon the sum of: (i) 54,781,950 shares of common stock outstanding as of November 5, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on November 10, 2025 and (ii) 8,581,250 shares of common stock issued in the February 2026 Offering as disclosed in the Issuer's Current Report on Form 8-K filed with the SEC on February 26, 2026, and giving effect to stock options, to the extent exercisable within 60 days hereof, as referenced herein.
(b)	Rows 7 through 10 of each Reporting Person's cover page to this Schedule 13D/A set forth the number of shares of common stock as to which such Reporting Person has the sole or shared power to vote or direct the vote and sole or shared power to dispose or to direct the disposition and are incorporated by reference.
(c)	Except as set forth herein, none of the Reporting Persons has effected any transactions with respect to the securities of the Issuer during the past sixty days.
(d)	No person (other than the Reporting Persons) is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the securities subject to this Schedule 13D/A.
(e)	Not applicable.
Item 7.	Material to be Filed as Exhibits.
	Exhibit 99.1 Joint Filing Agreement (incorporated by reference to Exhibit 1 to the Reporting Persons' Schedule 13D filed with the SEC on September 23, 2024).

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

RA Capital Management, L.P.

Signature:	/s/ Peter Kolchinsky
Name/Title:	By Peter Kolchinsky, Authorized Signatory
Date:	03/02/2026

Peter Kolchinsky

Signature:	/s/ Peter Kolchinsky
Name/Title:	Peter Kolchinsky
Date:	03/02/2026

Rajeev Shah

Signature:	/s/ Rajeev Shah
Name/Title:	Rajeev Shah
Date:	03/02/2026

RA Capital Healthcare Fund, L.P.

Signature:	/s/ Peter Kolchinsky
Name/Title:	By RA Capital Healthcare Fund GP, LLC, its General Partner, By Peter Kolchinsky, Manager
Date:	03/02/2026

FAQ

What ownership stake does RA Capital report in Bicara Therapeutics (BCAX)?

RA Capital and related entities report beneficial ownership of 7,279,739 Bicara Therapeutics common shares, representing 11.5% of the outstanding class. This figure is based on previously reported shares outstanding plus shares issued in Bicara’s February 2026 public offering and certain exercisable stock options.

How many Bicara Therapeutics (BCAX) shares does the RA Capital Healthcare Fund directly hold?

RA Capital Healthcare Fund, L.P. directly holds 4,603,418 Bicara Therapeutics common shares, representing 7.3% of the class. These shares form part of the total 7,279,739 shares reported as beneficially owned by the broader RA Capital reporting group in this Schedule 13D/A amendment.

What securities did RA Capital purchase in Bicara’s February 2026 offering?

On February 26, 2026, the Fund bought 300,000 Bicara common shares at $16.00 each and 2,200,000 pre-funded warrants at $15.9999 each. These purchases were made from the underwriters of Bicara’s public offering using the Fund’s working capital.

What is the total amount RA Capital paid in Bicara’s February 2026 offering?

The Fund paid an aggregate $39,999,780 in Bicara’s February 2026 offering. This total covers the purchase of 300,000 common shares at $16.00 per share and 2,200,000 pre-funded warrants at $15.9999 each, funded entirely from the Fund’s working capital.

How do the pre-funded warrants affect RA Capital’s Bicara ownership?

The Fund’s pre-funded warrants provide the right to acquire 2,200,000 Bicara shares but include a 9.99% beneficial ownership blocker. This prevents exercising the warrants if it would cause the Fund, affiliates, and attribution parties to own more than 9.99% of Bicara’s outstanding common stock.

How were RA Capital’s Bicara ownership percentages calculated in this filing?

Ownership percentages use 54,781,950 Bicara shares outstanding as of November 5, 2025 plus 8,581,250 shares issued in the February 2026 offering. The calculation also gives effect to stock options exercisable within 60 days, as referenced in the Schedule 13D/A amendment.