Sutro Biopharma director granted 10,000 stock options

SUTRO BIOPHARMA, INC. director Jon Marc Wigginton received a grant of stock options covering 10,000 shares of common stock on June 5, 2026.

Rhea-AI Filing Summary

SUTRO BIOPHARMA, INC. director Jon Marc Wigginton received a grant of stock options covering 10,000 shares of common stock on June 5, 2026. The options have an exercise price of $26.09 per share and represent equity-based compensation rather than an open-market trade.

According to the vesting terms, 8.33% of the award vests monthly starting on July 5, 2026, subject to his continued service. The options will be fully vested and exercisable on the earlier of the company’s 2027 annual stockholders meeting or June 5, 2027. Following this grant, he holds 10,000 options directly.

Insider Trade Summary

Grant/Award: 10,000 shares

Grant/Award 1 txn

Insider Wigginton Jon Marc

Role Director

Type	Security	Shares	Price	Value
Grant/Award	Stock Option (right to buy)	10,000	$0.00	$0.00

Holdings After Transaction: Stock Option (right to buy) — 10,000 contracts (Direct)

Footnotes (1)

1. F1. The option shall vest, subject to the reporting person's provision of service to the issuer on each vesting date, as to 8.33% of the total award monthly, with the first tranche vesting on July 5, 2026, and the award shall be fully vested and exercisable on the earlier of (i) the date of the issuer's 2027 annual stockholders meeting or (ii) June 5, 2027.

Key Figures

Option grant size: 10,000 options Exercise price: $26.09 per share Underlying shares: 10,000 shares +3 more

6 metrics

Option grant size 10,000 options Stock Option (right to buy) granted June 5, 2026

Exercise price $26.09 per share Exercise price for 10,000 option shares

Underlying shares 10,000 shares Common Stock underlying granted options

Post-grant holdings 10,000 options Total options held following transaction

Expiration date June 5, 2036 Option expiration for this grant

Monthly vesting rate 8.33% of award Vests monthly beginning July 5, 2026

Key Terms

Stock Option (right to buy), exercise price, vesting, annual stockholders meeting

4 terms

Stock Option (right to buy) financial

"security_title: Stock Option (right to buy)"

exercise price financial

"conversion_or_exercise_price: 26.0900"

The exercise price is the fixed amount at which you can buy or sell an asset, like a stock, when using an options contract. It matters because it helps determine whether exercising the option will be profitable or not, depending on the current market price. Think of it as the set price you agree on today to buy or sell later.

vesting financial

"The option shall vest, subject to the reporting person's provision of service"

Vesting is the process by which you earn full ownership of something, like company stock or a retirement benefit, over time. It’s like earning the right to keep a gift piece by piece the longer you stay with a company, making sure employees stay committed before they receive all the benefits.

annual stockholders meeting financial

"the issuer's 2027 annual stockholders meeting"

FAQ

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

What did Sutro Biopharma (STRO) director Jon Marc Wigginton report on this Form 4?

Jon Marc Wigginton reported receiving a grant of stock options for 10,000 shares of Sutro Biopharma common stock. The options are part of his equity compensation and do not reflect an open-market purchase or sale of existing STRO shares.

How many Sutro Biopharma (STRO) options were granted to Jon Marc Wigginton and at what price?

He was granted stock options covering 10,000 shares of Sutro Biopharma common stock at an exercise price of $26.09 per share. This means he can buy shares at $26.09 once the options vest and become exercisable under the grant terms.

What are the vesting terms of Jon Marc Wigginton’s Sutro Biopharma (STRO) option grant?

The option vests as to 8.33% of the total 10,000-share award each month, starting July 5, 2026. Vesting is conditioned on his continued service, with full vesting by the earlier of the 2027 annual stockholders meeting or June 5, 2027.

Is Jon Marc Wigginton buying or selling Sutro Biopharma (STRO) stock in this filing?

This filing reflects a grant of stock options, not a market purchase or sale of Sutro Biopharma shares. The transaction is categorized as a grant or award acquisition and is typical equity compensation for a company director.

How many Sutro Biopharma (STRO) options does Jon Marc Wigginton hold after this grant?

After this transaction, Jon Marc Wigginton holds 10,000 stock options directly according to the filing. These options give him the right to acquire 10,000 shares of common stock at an exercise price of $26.09 per share once vested.

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

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Accepted by SEC EDGAR 06/09/2026 - 04:24 PM Learn about SEC filing dates

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).

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^*

Wigginton Jon Marc

(Last) (First) (Middle)

C/O SUTRO BIOPHARMA, INC.

111 OYSTER POINT BLVD.

(Street)

SOUTH SAN FRANCISCO CALIFORNIA 94080

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
SUTRO BIOPHARMA, INC. [ STRO ]

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

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/05/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

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

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
Stock Option (right to buy)	$26.09	06/05/2026		A		10,000		(1)	06/05/2036	Common Stock	10,000	$0	10,000	D

Explanation of Responses:

1. The option shall vest, subject to the reporting person's provision of service to the issuer on each vesting date, as to 8.33% of the total award monthly, with the first tranche vesting on July 5, 2026, and the award shall be fully vested and exercisable on the earlier of (i) the date of the issuer's 2027 annual stockholders meeting or (ii) June 5, 2027.

	/s/ David Pauling as attorney-in-fact	06/09/2026
	** 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.
* Form 4: SEC 1474 (03-26)