Tectonic Therapeutic (TECX) CMO sells 10,000 shares in Rule 10b5-1 plan

Rhea-AI Filing Summary

Tectonic Therapeutic, Inc. Chief Medical Officer Marcella K. Ruddy reported an open-market sale of 10,000 shares of common stock on March 6, 2026 at a price of $30.00 per share. After this transaction, she directly holds 69,747 shares of the company’s common stock.

The sale was executed under a Rule 10b5-1 trading plan that she adopted on April 8, 2025, indicating the trades were pre-arranged under that plan rather than timed at her discretion.

Insider Trade Summary

Net Seller: 10,000 shares ($300,000)

Net Sell 1 txn

Insider Ruddy Marcella K.

Role Chief Medical Officer

Sold 10,000 shs ($300K)

Type	Security	Shares	Price	Value
Sale	Common Stock	10,000	$30.00	$300K

Holdings After Transaction: Common Stock — 69,747 shares (Direct)

Footnotes (1)

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Form 4 Insider Transactions: What Each Field Means →

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

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

X

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)
03/06/2026

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	03/06/2026		S(1)		10,000	D	$30	69,747	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 sale was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on April 8, 2025.

	/s/ Daniel Lochner, Attorney-in-Fact	03/09/2026
	** 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).
** 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.

FAQ

What insider transaction did Tectonic Therapeutic (TECX) report for Marcella K. Ruddy?

Tectonic Therapeutic’s Chief Medical Officer, Marcella K. Ruddy, reported selling 10,000 shares of common stock. The shares were sold in an open-market transaction at $30.00 per share on March 6, 2026, according to a Form 4 filing.

At what price were the TECX shares sold in Marcella K. Ruddy’s Form 4 filing?

The reported Tectonic Therapeutic (TECX) shares were sold at $30.00 per share. This price applies to the entire block of 10,000 common shares sold in the open market on March 6, 2026, as disclosed in the insider transaction report.

How many Tectonic Therapeutic (TECX) shares does Marcella K. Ruddy own after the sale?

After the reported sale, Marcella K. Ruddy directly owns 69,747 shares of Tectonic Therapeutic common stock. This post-transaction balance reflects her remaining direct holdings following the disposition of 10,000 shares in the March 6, 2026 open-market sale.

Was the TECX insider sale by Marcella K. Ruddy under a Rule 10b5-1 plan?

Yes. The filing states the sale was made under a Rule 10b5-1 trading plan adopted by Marcella K. Ruddy on April 8, 2025. Such plans pre-arrange trades, helping separate them from ad hoc timing decisions by insiders.

What role does Marcella K. Ruddy hold at Tectonic Therapeutic (TECX)?

Marcella K. Ruddy serves as the Chief Medical Officer of Tectonic Therapeutic, Inc. Her position as an executive officer makes her a reporting person for insider transactions, requiring Form 4 filings when she trades company common stock.

What transaction code was used in the TECX Form 4 for Marcella K. Ruddy?

The transaction is coded “S”, which the filing describes as a sale in open market or private transaction. This code confirms the 10,000-share disposition of Tectonic Therapeutic common stock was reported as a sale rather than an acquisition.