Jane Chung - 12 Dec 2025 Form 4 Insider Report for SUTRO BIOPHARMA, INC. (STRO)

Reporting relationship: Chief Executive Officer, Director
Issuer ticker: STRO
Reported as of: 12 Dec 2025
Net transaction value: -$7,165
SEC form: 4
Accepted by SEC: 16 Dec 2025, 20:47:26 UTC
Prior SEC filing: 16 Oct 2025
Next SEC filing: 03 Mar 2026
Source filing: View source filing
Reporting owner signature: /s/ David Pauling as attorney-in-fact for Jane Chung

Key filing fact

Jane Chung filed Form 4 for SUTRO BIOPHARMA, INC. (STRO) on 16 Dec 2025.

Key facts

This page summarizes Jane Chung's Form 4 filing for SUTRO BIOPHARMA, INC. (STRO).
3 reported transactions and 1 derivative row are listed below.
Accepted by SEC: 16 Dec 2025, 20:47.

Change

Previous filing in this sequence was filed on 16 Oct 2025.
Current net transaction value: -$7,165.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001872398 Primary reporting owner

Chung Jane

Relationship: Chief Executive Officer, Director
Address: C/O SUTRO BIOPHARMA, INC., 111 OYSTER POINT BLVD., SOUTH SAN FRANCISCO
Signature: /s/ David Pauling as attorney-in-fact for Jane Chung
Signature date: 16 Dec 2025

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

STRO transaction

Common Stock

Options Exercise

Transaction value: $0
Shares: +2,500
Change %: +20%
Price: $0.000000
Shares after: 14,785
Date: 12 Dec 2025
Ownership: Direct

STRO transaction

Common Stock

Tax liability

Transaction value: $7,165
Shares: -894
Change %: -6%
Price: $8.02
Shares after: 13,891
Date: 12 Dec 2025
Ownership: Direct
Footnotes: F1

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

STRO transaction Derivative

Restricted Stock Unit (RSU)

Options Exercise

Transaction value: $0
Shares: -2,500
Change %: -33%
Price: $0.000000
Shares after: 5,000
Date: 12 Dec 2025
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 2,500
Exercise price
Footnotes: F2, F3

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 3 footnotes

Footnote 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 RSUs; does not represent a sale by the reporting person.

Footnote F2

Each RSU represents a contingent right to receive one share of the Issuer's Common Stock upon settlement.

Footnote F3

The RSU award vested or vests as to 1/4th of the total award annually, subject to continued service through each vesting date, with the first tranche vested on December 1, 2024. The reported transaction represents the deferred vesting and settlement of a tranche of this award pursuant to the terms of the reporting person's award agreement with the Issuer.

SEC remarks

Effective as of 12:01 a.m. Eastern time on December 3, 2025, pursuant to a Certificate of Amendment to the Issuer's Restated Certificate of Incorporation previously approved by the Issuer's stockholders, and filed with the Delaware Secretary of State on December 2, 2025, the Issuer's Common Stock, par value $0.001 per share, underwent a 1-for-10 reverse stock split (the "Reverse Stock Split"). All amounts, including all dollar values, set forth herein have been adjusted to reflect the Reverse Stock Split.