Ambrose Allison 4

What Happened Ambrose Allison, General Counsel of Upstream Bio, sold 477 shares on 2026-06-16 at $6.10 per share, generating $2,910 of proceeds. The filing classifies the transaction as a sale and notes the shares were sold to satisfy tax withholding obligations tied to the vesting of restricted stock units.

Key Details

• Transaction date: 2026-06-16
• Transaction type/code: Sale (S) — open market or private sale
• Price per share: $6.10; shares sold: 477; proceeds: $2,910
• Shares owned after transaction: Not disclosed in the supplied filing
• Footnote: The sale was an automatic "sell-to-cover" to satisfy tax withholding on RSU vesting (automatic, not at the reporting person's discretion)
• Filing date: 2026-06-17 — filed promptly (Form 4 is generally due within two business days)

Context Sell-to-cover transactions are routine administrative sales to cover tax on vested awards and do not necessarily reflect an insider's view of the company. The size of this sale is small; retail investors typically view purchases as a stronger signal than routine withholding sales.