Deykin Aaron 4

What Happened Aaron Deykin, Chief Medical Officer of Upstream Bio (UPB), sold 894 shares on 2026-03-16 at $9.29 per share, generating proceeds of about $8,305. The sale was reported as a disposition (Code S) and reflects shares sold to cover tax withholding related to vested restricted stock units, not a discretionary open-market investment decision.

Key Details

• Transaction date and price: 2026-03-16, 894 shares at $9.29 each.
• Gross proceeds: approximately $8,305.
• Shares owned after transaction: not specified in this Form 4.
• Footnote: Issuer adopted a "sell-to-cover" policy—these sales were automatic to satisfy tax withholding on RSU vesting and were not at the Reporting Person's discretion (Footnote F1).
• Filing timeliness: Report filed 2026-03-17 (timely; within required reporting window).

Context Sell-to-cover transactions are routine tax-withholding actions when restricted stock units vest; they generally do not indicate a judgment about the company's prospects. For retail investors, purchases tend to be more informative than small, automatic sales like this one.