Upstream Bio (UPB) General Counsel Ambrose Allison Sells 485 Shares

What Happened

Ambrose Allison, General Counsel of Upstream Bio, sold 485 shares on 2026-09-16 at $5.49 per share, for a total of $2,663. The Form 4 reports this as a sale (code S), and the filing indicates the sale was an automatic "sell-to-cover" to satisfy tax withholding related to vesting restricted stock units (RSUs), not an active decision to liquidate equity.

Key Details

• Transaction date: 2026-09-16
• Price per share: $5.49; total proceeds: $2,663
• Transaction type: Sale (S) — reported as sell-to-cover for RSU tax withholding (footnote F1)
• Shares owned after transaction: Not disclosed in the provided filing summary
• Filing date: 2026-09-17 — filed the next day (timely under Form 4 rules)
• Footnote: F1 clarifies the sales were automatic under the issuer's sell-to-cover policy to satisfy tax withholding and were not at the Reporting Person's discretion.

Context

Sell-to-cover transactions are routine when RSUs vest and typically reflect tax-liability handling rather than a directional view on the company's stock. Such automatic sales should not be interpreted as a strong signal about insider sentiment; purchases or voluntary sales are generally more informative for assessing insider conviction.