Sutro Biopharma (STRO) director receives grant of 10,000 stock options

Rhea-AI Filing Summary

Sutro Biopharma director Michael Dybbs received a new stock option grant. He was awarded options for 10,000 shares of common stock at an exercise price of $26.09 per share. These options were granted at no upfront cost and increase his potential future equity stake.

The award vests monthly at 8.33% of the total starting on July 5, 2026, and will be fully vested and exercisable on the earlier of the company’s 2027 annual stockholders meeting or June 5, 2027, as long as he continues providing service.

Insights

Equity compensation analyst

Routine director option grant with time-based vesting.

Director Michael Dybbs received a grant of options for 10,000 shares of Sutro Biopharma common stock at an exercise price of $26.09 per share. The Form 4 classifies this as a grant or award acquisition rather than a market transaction.

The options vest in monthly installments of 8.33% beginning on July 5, 2026, becoming fully vested by the earlier of the 2027 annual stockholders meeting or June 5, 2027, contingent on continued service. This is standard governance-aligned compensation, not a buy or sell signal, and is best viewed as routine equity-based pay.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Dybbs Michael

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 Exercise price: $26.09 per share Shares underlying options: 10,000 shares +5 more

8 metrics

Option grant size 10,000 options Stock Option (right to buy) awarded to director

Exercise price $26.09 per share Conversion or exercise price for common stock

Shares underlying options 10,000 shares Underlying common stock covered by the grant

Post-grant derivative holding 10,000 options Total options following this transaction

Vesting rate 8.33% monthly Portion of total award vesting each month

Vesting start date July 5, 2026 First monthly vesting tranche date

Latest full vesting date June 5, 2027 Outside date for full vesting if earlier meeting not held

Option expiration June 5, 2036 Expiration date of the stock option grant

Key Terms

Stock Option (right to buy), Grant, award, or other acquisition, exercise price, vesting, +2 more

6 terms

Stock Option (right to buy) financial

"security_title: Stock Option (right to buy)"

Grant, award, or other acquisition financial

"transaction_code_description: Grant, award, or other acquisition"

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"

exercisable financial

"the award shall be fully vested and exercisable on the earlier of"

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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^*

Dybbs Michael

(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 Michael Dybbs report on this Form 4?

Director Michael Dybbs reported receiving a stock option grant for 10,000 shares of Sutro Biopharma common stock. The options were awarded at an exercise price of $26.09 per share as equity compensation, not as an open-market stock purchase or sale.

How many Sutro Biopharma (STRO) shares are covered by Michael Dybbs’ new options?

The new grant covers options on 10,000 shares of Sutro Biopharma common stock. After this award, his total reported derivative holdings from this grant are 10,000 options, all subject to future vesting and later exercise at the stated strike price.

What is the exercise price of Michael Dybbs’ Sutro Biopharma (STRO) stock options?

The options have an exercise price of $26.09 per share, meaning Dybbs can buy common stock at that price once vested and exercised. This price is fixed in the grant terms and applies through the option’s life until its expiration date.

How do Michael Dybbs’ Sutro Biopharma (STRO) options vest over time?

The option vests in monthly installments of 8.33% of the total award, starting July 5, 2026. Vesting depends on Dybbs continuing to provide service, with the entire award fully vested by the earlier of the 2027 annual stockholders meeting or June 5, 2027.

When do Michael Dybbs’ new Sutro Biopharma (STRO) options fully vest and become exercisable?

The options become fully vested and exercisable on the earlier of Sutro Biopharma’s 2027 annual stockholders meeting or June 5, 2027. Full vesting still requires that Dybbs continue to provide service to the company through the applicable vesting dates.

Is this Sutro Biopharma (STRO) Form 4 a stock purchase or sale by Michael Dybbs?

No, this Form 4 reports a grant of stock options, not an open-market purchase or sale. It is classified as a grant, award, or other acquisition, reflecting routine equity compensation rather than an active trading decision in Sutro Biopharma shares.