Sutro Biopharma (STRO) director granted 10,000 stock options at $26.09

Rhea-AI Filing Summary

Sutro Biopharma director Daniel H. Petree received a grant of stock options for 10,000 shares of Common Stock on June 5, 2026. The options have an exercise price of $26.09 per share and expire on June 5, 2036.

The award vests monthly as to 8.33% of the total, starting July 5, 2026, provided he continues to provide services. The options will be fully vested and exercisable on the earlier of the company’s 2027 annual stockholders meeting or June 5, 2027.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Petree Daniel H

Role null

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

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

Footnotes (1)

1. [object Object]

Key Figures

Option grant size: 10,000 options Underlying shares: 10,000 shares Exercise price: $26.09 per share +4 more

7 metrics

Option grant size 10,000 options Stock Option grant on June 5, 2026

Underlying shares 10,000 shares Common Stock underlying granted options

Exercise price $26.09 per share Conversion or exercise price of options

Expiration date June 5, 2036 Option expiration

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

Full vesting date Earlier of 2027 meeting or June 5, 2027 Fully vested and exercisable cutoff

Post-transaction options 10,000 options Total options held after this grant

Key Terms

Stock Option, exercise price, vesting, annual stockholders meeting

4 terms

Stock Option financial

"Stock Option (right to buy)"

A stock option is a contract that gives you the right to buy or sell a company's stock at a specific price within a certain time frame. People use them to potentially make money if the stock's price moves favorably or to protect against losses. It's like holding a coupon that can be used to buy or sell stock at a set price later on.

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"

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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).

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^*

Petree Daniel H

(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)

FAQ

What did Sutro Biopharma (STRO) director Daniel H. Petree report on this Form 4?

Director Daniel H. Petree reported receiving a grant of stock options for 10,000 shares of Sutro Biopharma Common Stock. The options were granted on June 5, 2026, as a compensation-related award rather than an open-market stock purchase or sale.

What are the key terms of Daniel Petree’s new Sutro Biopharma stock options?

The grant covers 10,000 shares of Common Stock at an exercise price of $26.09 per share. These stock options expire on June 5, 2036, giving a long exercise window once they have vested according to the specified schedule.

How do Daniel Petree’s Sutro Biopharma options vest over time?

The options vest as to 8.33% of the total award each month, starting July 5, 2026, contingent on continued service. They will be fully vested and exercisable by the earlier of the 2027 annual stockholders meeting or June 5, 2027.

Is Daniel Petree’s Form 4 transaction a market buy or sell of STRO shares?

The Form 4 shows a grant of stock options, not a market buy or sell of existing STRO shares. This is a compensation-related acquisition coded as a grant/award, with no open-market trading reported in this filing.

How many Sutro Biopharma options does Daniel Petree hold after this grant?

Following the reported transaction, Daniel Petree holds 10,000 stock options related to Sutro Biopharma Common Stock. These options correspond to 10,000 underlying shares once vested and exercised at the $26.09 per share exercise price.