Jane Chung - 01 Mar 2026 Form 4 Insider Report for SUTRO BIOPHARMA, INC. (STRO)

Role: Chief Executive Officer, Director
Signature: /s/ David Pauling as attorney-in-fact
Issuer symbol: STRO
Transactions as of: 01 Mar 2026
Net transactions value: -$83,126
Form type: 4
Filing time: 03 Mar 2026, 18:48:50 UTC
Previous filing: 16 Dec 2025
Next filing: 06 Mar 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Chung Jane	Chief Executive Officer, Director	C/O SUTRO BIOPHARMA, INC., 111 OYSTER POINT BLVD., SOUTH SAN FRANCISCO	/s/ David Pauling as attorney-in-fact	03 Mar 2026	0001872398

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	STRO	Common Stock	Options Exercise	$0	+688	+5%	$0.000000	14,579	01 Mar 2026	Direct
transaction	STRO	Common Stock	Options Exercise	$0	+2,500	+17%	$0.000000	17,079	01 Mar 2026	Direct
transaction	STRO	Common Stock	Tax liability	$26,017	-1,271	-7.4%	$20.47	15,808	01 Mar 2026	Direct	F1
transaction	STRO	Common Stock	Options Exercise	$0	+7,750	+49%	$0.000000	23,558	02 Mar 2026	Direct
transaction	STRO	Common Stock	Tax liability	$57,108	-2,779	-12%	$20.55	20,779	02 Mar 2026	Direct	F1

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
transaction	STRO	Restricted Stock Units (RSUs)	Options Exercise	$0	-688	-50%	$0.000000	688	01 Mar 2026	Common Stock	688		Direct	F2, F3
transaction	STRO	Restricted Stock Units (RSUs)	Options Exercise	$0	-2,500	-33%	$0.000000	5,000	01 Mar 2026	Common Stock	2,500		Direct	F2, F4
transaction	STRO	Restricted Stock Units (RSUs)	Options Exercise	$0	-7,750	-25%	$0.000000	23,250	02 Mar 2026	Common Stock	7,750		Direct	F2, F5
transaction	STRO	Restricted Stock Units (RSUs)	Award	$0	+40,000		$0.000000	40,000	02 Mar 2026	Common Stock	40,000		Direct	F2, F6
transaction	STRO	Stock Option (right to buy)	Award	$0	+175,000		$0.000000	175,000	02 Mar 2026	Common Stock	175,000	$20.55	Direct	F7

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	Represents the number of shares of Common Stock that have been withheld by the Issuer to satisfy its income tax withholding and remittance obligations in connection with the net settlement of restricted stock units; does not represent a sale by the reporting person.
F2	Each RSU represents a contingent right to receive one (1) share of the Issuer's Common Stock upon settlement.
F3	The RSUs vested or vest as to 1/4 of the total award annually, with the first tranche vested on March 1, 2024, subject to continued service through each vesting date.
F4	The RSUs vested or vest as to 1/4 of the total award annually, with the first tranche vested on March 1, 2025, subject to continued service through each vesting date.
F5	The RSUs vested or vest as to 1/4 of the total award annually, with the first tranche vested on March 2, 2026, subject to continued service through each vesting date.
F6	The RSUs shall vest as to 1/4 of the total award annually, with the first tranche vesting on March 1, 2027, subject to continued service through each vesting date.
F7	1/48 of the total option award shall vest monthly, subject to the reporting person's continued service through each vesting date, with the first tranche vesting on April 1, 2026.