Welcome to our dedicated page for Sutro Biopharma SEC filings (Ticker: STRO), a comprehensive resource for investors and traders seeking official regulatory documents including 10-K annual reports, 10-Q quarterly earnings, 8-K material events, and insider trading forms.
The Sutro Biopharma, Inc. (STRO) SEC filings page on Stock Titan provides access to the company’s public filings as reported to the U.S. Securities and Exchange Commission. Sutro is a clinical-stage oncology company focused on antibody-drug conjugates (ADCs), and its filings offer detailed insight into how it reports financial results, manages risk, and discloses material events related to its ADC pipeline and corporate operations.
Investors can review current reports on Form 8-K, where Sutro has disclosed items such as quarterly financial results, organizational restructuring designed to prioritize its ADC programs and extend its cash runway, and notices from Nasdaq regarding minimum bid price compliance. Additional 8-K filings describe actions like the 1-for-10 reverse stock split of its common stock and subsequent confirmation that the company regained compliance with Nasdaq Listing Rule 5450(a)(1).
Beyond event-driven 8-Ks, users can use this page to locate annual reports on Form 10-K and quarterly reports on Form 10-Q, which typically contain more extensive information on Sutro’s research and development activities, collaboration agreements, and financial condition. For those tracking management and ownership changes, insider transaction reports on Form 4 and related filings can also be accessed to see how executives and directors transact in STRO shares.
Stock Titan enhances these documents with AI-powered summaries that highlight key points from lengthy filings, helping readers quickly understand topics such as pipeline updates, restructuring charges, collaboration revenue, and listing status developments. Real-time updates from EDGAR ensure that new Sutro Biopharma filings appear promptly, while AI-generated overviews provide a starting point for deeper review of the full SEC documents.
Sutro Biopharma is registering up to $100.0 million of common stock for sale under a Sales Agreement with TD Securities (USA) LLC (TD Cowen) pursuant to an at-the-market program. Sales may occur from time to time in negotiated transactions, block trades or other methods permitted under Rule 415.
The shares trade on Nasdaq under the symbol STRO (last reported sale $24.91 on March 31, 2026). The prospectus supplement states there were 8,584,309 shares outstanding as of December 31, 2025 and discloses dilution and net tangible book value metrics tied to an illustrative $100.0 million placement.
Sutro Biopharma, Inc. filed a shelf registration and preliminary prospectus permitting up to $300.0 million of securities and a prospectus supplement enabling an at-the-market program to sell up to $100.0 million of common stock through TD Securities (USA) LLC (TD Cowen) as agent or principal. The sales agreement contemplates negotiated transactions and at-the-market distributions, with compensation to TD Cowen of up to 3.0% of gross proceeds. The company reported 8,584,309 shares outstanding as of December 31, 2025, and the last reported sale price was $21.12 per share on March 19, 2026.
Sutro Biopharma is a clinical-stage oncology company focused on next‑generation antibody-drug conjugates (ADCs) built on its proprietary cell-free protein synthesis platforms XpressCF® and XpressCF+®. Its lead wholly owned program, STRO‑004, targets tissue factor in multiple solid tumors and entered a Phase 1 trial in late 2025, with initial data expected in mid‑2026.
Preclinical assets include STRO‑006 (ITGβ6‑targeted ADC) and STRO‑227 (dual‑payload PTK7‑targeted ADC), with planned IND filings between 2026 and early 2027. The company highlights its ability to precisely place non‑natural amino acids to create homogeneous, high‑DAR ADCs and dual‑payload constructs, including immunostimulatory ADCs (iADCs) and dpADCs.
Sutro reports aggregate collaboration payments of about $1.016 billion through December 31, 2025, including a $90.0 million upfront from Astellas and a $140.0 million royalty monetization with Blackstone tied to Vaxcyte vaccines. Market value of non‑affiliate equity was approximately $60.0 million as of June 30, 2025, with 16,567,238 shares outstanding as of March 16, 2026.
Sutro Biopharma, Inc. filed an 8-K announcing termination of its Open Market Sale Agreement with Jefferies, ending its at-the-market equity program, and reporting full-year 2025 results. After the termination, no additional common shares may be sold under that agreement.
For 2025, revenue grew to $102.5 million from $62.0 million in 2024, mainly from Astellas and Ipsen collaborations. Total operating expenses fell to $260.9 million from $300.5 million, even including $53.4 million of restructuring and related costs.
The company reported a net loss of $191.1 million, improved from a $227.5 million loss in 2024, with basic and diluted net loss per share of $22.49. Cash, cash equivalents and marketable securities were $141.4 million as of December 31, 2025, and a recent $110.0 million equity financing extended its cash runway into at least the second quarter of 2028. Sutro highlighted progress across its ADC pipeline, including STRO-004 Phase 1 dosing, planned 2026 INDs for STRO-006 and STRO-227, and Astellas-partnered dual-payload programs generating $17.5 million in milestones.
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.