Tectonic Therapeutic (TECX) withholds 2,064 CMO shares for taxes

Rhea-AI Filing Summary

Tectonic Therapeutic, Inc. reported that Chief Medical Officer Marcella K. Ruddy had 2,064 shares of common stock withheld on February 4, 2026. The company withheld these shares to cover her tax obligations related to the vesting and settlement of restricted stock units granted on February 4, 2025. After this tax withholding, she directly beneficially owned 53,247 common shares of Tectonic Therapeutic.

SEC Form 4

FORM 4

UNITED 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

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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^*

Ruddy Marcella K.

(Last) (First) (Middle)

C/O TECTONIC THERAPEUTIC, INC.

490 ARSENAL WAY, SUITE 200

(Street)

WATERTOWN MA 02472

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Tectonic Therapeutic, Inc. [ TECX ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Medical Officer

3. Date of Earliest Transaction (Month/Day/Year)
02/04/2026

4. 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 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)
			Code	V	Amount	(A) or (D)	Price
Common Stock	02/04/2026		F		2,064(1)	D	$23.22	53,247	D

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)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. This transaction reported represents the withholding of shares by the Issuer to satisfy the Reporting Person's tax withholding obligations in connection with the vesting and settlement of the restricted stock units granted on February 4, 2025.

	/s/ Daniel Lochner, Attorney-in-Fact	02/10/2026
	** 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).
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FAQ

What insider transaction did Tectonic Therapeutic (TECX) report for February 4, 2026?

Tectonic Therapeutic reported that its Chief Medical Officer, Marcella K. Ruddy, had 2,064 common shares withheld on February 4, 2026. The issuer used these shares to cover her tax withholding obligations tied to restricted stock units that vested and settled from a February 4, 2025 grant.

How many Tectonic Therapeutic (TECX) shares were withheld for taxes in this Form 4?

The filing shows that 2,064 shares of Tectonic Therapeutic common stock were withheld. The issuer applied these shares to satisfy Chief Medical Officer Marcella K. Ruddy’s tax withholding obligations arising from the vesting and settlement of previously granted restricted stock units dated February 4, 2025.

How many Tectonic Therapeutic (TECX) shares does the reporting officer own after the transaction?

After the reported transaction, Chief Medical Officer Marcella K. Ruddy beneficially owned 53,247 shares of Tectonic Therapeutic common stock directly. This figure reflects her holdings following the issuer’s withholding of 2,064 shares to cover tax obligations linked to her restricted stock unit vesting.

Who is the reporting person in this Tectonic Therapeutic (TECX) Form 4 filing?

The reporting person is Marcella K. Ruddy, who serves as Chief Medical Officer of Tectonic Therapeutic, Inc. She filed individually, and the Form 4 details a tax-related withholding of 2,064 common shares by the issuer connected to the vesting of restricted stock units.

What is the nature of the Tectonic Therapeutic (TECX) share transaction coded "F" in this report?

The transaction represents the issuer’s withholding of 2,064 common shares to satisfy tax withholding obligations. These obligations arose when restricted stock units granted on February 4, 2025, vested and settled, rather than an open market purchase or sale by Chief Medical Officer Marcella K. Ruddy.

At what price per share were the withheld Tectonic Therapeutic (TECX) shares valued?

The 2,064 withheld common shares were valued at $23.22 per share. This per-share value appears in the transaction table and applies to the shares used by Tectonic Therapeutic to cover Chief Medical Officer Marcella K. Ruddy’s tax withholding obligations upon restricted stock unit vesting.