GRAY MICHAEL 4

What Happened
Michael Gray, Chief Financial Officer and Chief Operating Officer of Upstream Bio (UPB), reported a sale of 853 shares on 2026-06-16 at $6.10 per share, generating proceeds of $5,203. The transaction is reported as an open market or private sale (code S) and reflects shares sold to cover tax withholding related to restricted stock unit vesting rather than a discretionary sale.

Key Details

• Transaction date: 2026-06-16; filing date: 2026-06-17 (timely filing).
• Price per share: $6.10; shares sold: 853; gross proceeds: $5,203.
• Transaction code: S (Sale).
• Footnote: F1 — sale was an automatic "sell-to-cover" to satisfy tax withholding obligations upon RSU vesting; not at the Reporting Person's discretion.
• Shares owned after transaction: not specified in the provided filing details.

Context
Sell-to-cover transactions are routine administrative sales to satisfy tax withholding on vested awards and are commonly not interpreted as a signal of negative insider sentiment. For retail investors, purchases generally carry more weight as bullish signals; automatic, tax-related sales are procedural.