Every Form 4 that Sutro Biopharma, Inc. (STRO) has filed with the SEC in the last 12 months is listed below, newest first, and each one links through to the document itself with the summary and the scores our analysis gives it.
A Form 4 covers the transactions officers, directors and large holders report, so if you follow STRO and want that one kind of document rather than the whole filing history, this is the page to keep. The company's other filings, of every form, are on the full STRO filings page.
SUTRO BIOPHARMA, INC. director Jon Marc Wigginton received a grant of stock options covering 10,000 shares of common stock on June 5, 2026. The options have an exercise price of $26.09 per share and represent equity-based compensation rather than an open-market trade.
According to the vesting terms, 8.33% of the award vests monthly starting on July 5, 2026, subject to his continued service. The options will be fully vested and exercisable on the earlier of the company’s 2027 annual stockholders meeting or June 5, 2027. Following this grant, he holds 10,000 options directly.
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.
Sutro Biopharma director James P. Panek received a grant of stock options covering 10,000 shares of common stock. The options have an exercise price of $26.09 per share and expire on June 5, 2036. They vest 8.33% monthly starting July 5, 2026 and are fully exercisable by the earlier of the 2027 annual stockholders meeting or June 5, 2027, assuming continued service.
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.
Sutro Biopharma director Jagpal Sukhi received a new stock option grant for 10,000 shares of common stock. The option has an exercise price of $26.09 per share and expires on June 5, 2036. This is a compensation-related award rather than an open-market trade.
The option vests over time, with 8.33% of the total award vesting monthly, starting on July 5, 2026. The grant will be fully vested and exercisable on the earlier of the company’s 2027 annual stockholders meeting or June 5, 2027, assuming continued service. After this grant, Sukhi holds options to acquire 10,000 shares directly.
Sutro Biopharma director Heidi Hunter 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. Vesting occurs in 8.33% monthly installments starting July 5, 2026, and the award is fully vested by the earlier of the 2027 annual stockholders meeting or June 5, 2027.
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.
Sutro Biopharma director Connie Matsui received a new stock option grant covering 10,000 shares of Common Stock. The option has an exercise price of $26.09 per share and was granted as a compensation award, not an open-market purchase or sale. It vests in monthly installments of 8.33% starting on July 5, 2026. The award becomes fully vested and exercisable on the earlier of the company’s 2027 annual stockholders meeting or June 5, 2027, assuming continued service.
Sutro Biopharma CFO Gregory K. Chow exercised equity awards and increased his direct stake in the company. On June 2, 2026, he exercised Restricted Stock Units (RSUs) covering 2,500 shares of Common Stock, with no shares sold in this filing. Following the transaction, he directly holds 4,725 shares of Common Stock and 7,500 RSUs, each representing the right to receive one share upon settlement. Footnotes state that tax withholding obligations were satisfied in cash rather than by withholding shares, and that his total Common Stock holdings include 250 shares acquired under the company’s employee stock purchase plan.
SUTRO BIOPHARMA, INC. executive David Pauling, Chief Administrative Officer and General Counsel, reported equity transactions tied to restricted stock units on March 4, 2026. He exercised 675 RSUs, each converting into one share of common stock, and received 675 shares at a stated price of $0.00 per share.
To cover income tax withholding on this vesting, 277 common shares were withheld by the company at $21.31 per share, which the footnote clarifies does not represent a sale by Pauling. After these transactions, he directly owned 9,748 shares of Sutro Biopharma common stock.
SUTRO BIOPHARMA, INC. director and Chief Executive Officer Jane Chung reported equity award activity involving restricted stock units and common stock. On March 4, 2026, 788 restricted stock units were exercised or converted into 788 shares of common stock at a stated price of $0.00 per share, reflecting settlement of previously granted RSUs.
On the same date, 282 shares of common stock were withheld at a price of $21.31 per share to satisfy income tax withholding and remittance obligations related to the net settlement of the RSUs, and the footnote clarifies this does not represent a sale by the reporting person. After these transactions, Jane Chung directly owned 21,285 shares of Sutro Biopharma common stock.
SUTRO BIOPHARMA, INC. Chief Administrative Officer and General Counsel David Pauling reported multiple equity transactions. He acquired common stock through the vesting and settlement of restricted stock units (RSUs) and received new awards of 4,200 RSUs and stock options for 33,600 shares. Some common shares (970 and 551) were withheld at prices of $20.55 and $20.47 to satisfy tax obligations in connection with RSU settlements, which the company notes do not represent market sales by Pauling.
Sutro Biopharma Chief Scientific Officer Hans-Peter Gerber reported multiple equity transactions involving restricted stock units (RSUs), stock options and common shares. On March 1 and 2, 2026, RSU vesting led to the acquisition of 1,125 and 2,843 shares of common stock through derivative exercises at a stated price of $0.00 per share.
To cover income tax withholding obligations related to these RSU settlements, the issuer withheld 463 and 1,170 shares of common stock at prices of $20.47 and $20.55 per share, which the footnotes clarify do not represent sales by the reporting person. Gerber also received direct grants of 5,000 RSUs and a stock option for 40,000 shares, each subject to time-based vesting schedules described in the footnotes, including annual RSU vesting in four tranches and a stock option that vests in 1/48 monthly installments beginning on April 1, 2026.
SUTRO BIOPHARMA, INC. reported that its CFO, Gregory K. Chow, received new equity awards. He was granted stock options covering 40,000 shares of common stock at an exercise price of $0.00 per share, and 5,000 Restricted Stock Units (RSUs), both held directly.
According to the vesting terms, 1/48 of the stock option award vests monthly, starting on April 1, 2026, contingent on his continued service. The 5,000 RSUs vest in four equal annual installments, with the first tranche vesting on March 1, 2027, also subject to continued service, and each RSU represents one share upon settlement.
Sutro Biopharma CEO Jane Chung reported multiple equity award and vesting transactions. She received a grant of 40,000 Restricted Stock Units (RSUs) and a stock option for 175,000 shares, both with service-based vesting schedules over time.
RSUs previously granted to her vested on March 1 and March 2, 2026, and were settled into common stock through several derivative exercises. In connection with these vestings, a total of 2,779 shares at $20.55 and 1,271 shares at $20.47 of common stock were withheld by the company to cover income tax obligations, which the footnotes state do not represent sales by the reporting person.
Sutro Biopharma CEO and director Jane Chung reported the vesting and settlement of restricted stock units on 12/12/2025. She received 2,500 shares of common stock at an exercise price of $0, and 894 shares were withheld by the company at $8.015 per share to cover tax obligations, which the filing states does not represent a sale by her. Following these transactions, she directly owns 13,891 shares of common stock and 5,000 RSUs, each RSU representing the right to receive one share upon settlement. The award vests in annual quarters, with the first tranche having vested on December 1, 2024. All share and dollar amounts reflect a 1-for-10 reverse stock split of Sutro Biopharma common stock that became effective on December 3, 2025.
Sutro Biopharma (STRO) reported an insider purchase by its Chief Scientific Officer, Hans-Peter Gerber. On October 15, 2025, he bought 17,000 shares of common stock at a weighted average price of $0.8004 per share in open-market transactions. Following the trade, he beneficially owned 71,832 shares, held directly.
The filing notes the shares were acquired through multiple executions within a price range of $0.7932 to $0.8015, and provides to interested parties the breakdown of shares purchased at each price upon request.
Sutro Biopharma (STRO) reported an insider purchase on Form 4. CFO Gregory K. Chow bought 19,750 shares of common stock on 10/15/2025 with transaction code P (purchase). The weighted average price was $0.81, with individual trades executed between $0.8099 and $0.8100. Following the transaction, he beneficially owned 19,750 shares, held directly.
Sutro Biopharma (STRO) disclosed an insider stock purchase by its Chief Executive Officer and Director, Jane Chung. On 10/15/2025, the reporting person purchased 12,500 shares of common stock at $0.8009 per share (transaction code P). Following this transaction, the reporting person beneficially owned 122,850 shares, held in direct ownership.
No derivative securities were reported in this filing.
Sutro Biopharma (STRO) reported an insider share purchase. A director bought 50,000 shares of common stock on 10/15/2025 at a price of $0.799 per share, according to a Form 4 filing. Following the transaction, the reporting person beneficially owns 50,000 shares, held directly.
Sutro Biopharma (STRO): Insider transaction reported. A company officer (Chief Administrative Officer & General Counsel) purchased 12,504 shares of Common Stock on 10/15/2025 at $0.7992 per share, according to a Form 4 filing.
Following the transaction, the officer directly beneficially owns 71,737 shares. The total includes 2,500 shares acquired through the company’s Employee Stock Purchase Plan, as noted in the filing’s explanation.
Hans-Peter Gerber, Chief Scientific Officer of Sutro Biopharma, acquired equity and vested awards on 09/18/2025. The Form 4 shows 37,500 restricted stock units (RSUs) were recorded as acquired and will settle into common stock; each RSU converts to one share on settlement. Following the transactions, Mr. Gerber beneficially owned 75,000 shares of common stock. Additionally, the issuer withheld 13,417 shares