Sutro Biopharma director granted 10,000 stock options

Sutro Biopharma director Joseph M. Lobacki received a grant of stock options for 10,000 shares of common stock.

Accepted by SEC EDGAR 06/09/2026 - 04:19 PM EDT Learn about SEC filing dates

Rhea-AI Filing Summary

Sutro Biopharma director Joseph M. Lobacki received a grant of stock options for 10,000 shares of common stock. The options carry an exercise price of $26.09 per share and expire on June 5, 2036. Vesting is scheduled at 8.33% of the total award each month starting July 5, 2026, and the grant becomes fully vested and exercisable on the earlier of the company’s 2027 annual stockholders meeting or June 5, 2027, subject to his continued service.

Insider Trade Summary

Grant/Award: 10,000 shares

Grant/Award 1 txn

Insider Lobacki Joseph M

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 Option expiration: June 5, 2036 +1 more

4 metrics

Option grant size 10,000 options Stock Option (right to buy) covering common stock

Exercise price $26.09 per share Conversion or exercise price for option grant

Option expiration June 5, 2036 Expiration date of stock option award

Vesting schedule 8.33% of award monthly Monthly vesting starting July 5, 2026 until fully vested by 2027

Key Terms

Stock Option (right to buy), exercise price, expiration date, vesting

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.

expiration date financial

"expiration_date: 2036-06-05T00:00:00.000Z"

The expiration date is the deadline after which a financial contract, such as an option or a futures agreement, is no longer valid or can be exercised. It matters to investors because it determines the timeframe during which they can take action or benefit from the contract, similar to how a coupon or a food item has a limited period of usefulness. Once the expiration date passes, the contract loses its value or ability to be used.

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.

FAQ

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

What did Sutro Biopharma (STRO) director Joseph Lobacki receive in this Form 4?

Joseph M. Lobacki received a grant of stock options for 10,000 shares of Sutro Biopharma common stock. These options represent a compensation-related award rather than an open-market purchase or sale of existing shares.

What is the exercise price of Joseph Lobacki’s Sutro Biopharma options?

The stock options granted to Joseph M. Lobacki have an exercise price of $26.09 per share. This is the fixed price at which he can buy Sutro Biopharma common shares once the options vest and are exercised.

When do Joseph Lobacki’s Sutro Biopharma options expire?

The stock options granted to Joseph M. Lobacki expire on June 5, 2036. After this expiration date, any unexercised options will no longer be exercisable, regardless of whether they had previously vested under the award terms.

How do Joseph Lobacki’s Sutro Biopharma options vest over time?

The options vest as to 8.33% of the total award each month, beginning July 5, 2026. The grant becomes fully vested and exercisable on the earlier of Sutro’s 2027 annual stockholders meeting or June 5, 2027, assuming continued service.

Is Joseph Lobacki’s Form 4 transaction a market buy or sell of STRO shares?

No, the Form 4 shows a grant of stock options as compensation, coded as an acquisition (A). It does not represent an open-market purchase or sale of Sutro Biopharma common stock by Joseph M. Lobacki.

How many Sutro Biopharma shares are covered by Joseph Lobacki’s new options?

The stock option award covers 10,000 shares of Sutro Biopharma common stock. Each option, once vested and exercised at the $26.09 per share exercise price, entitles him to receive one share of common stock.

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

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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^*

Lobacki Joseph M

(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)