Upstream Bio (UPB) CMO Aaron Deykin Sells 895 Shares

What Happened

• Aaron Deykin, Chief Medical Officer of Upstream Bio (UPB), sold 895 shares on 2026-09-16 in an open-market or private sale. The shares were sold at $5.49 each for total proceeds of $4,914. This sale was reported on a Form 4 filed 2026-09-17.

Key Details

• Transaction date & price: 2026-09-16 — 895 shares at $5.49 per share (total $4,914).
• Transaction type: Sale (reported as open market or private sale).
• Shares owned after transaction: Not disclosed on this Form 4.
• Footnote: The filing includes a sell-to-cover note (F1) — the sale was automatic to satisfy tax withholding obligations related to RSU vesting and was not at the Reporting Person’s discretion.
• Filing timeliness: Filed 2026-09-17 for a 2026-09-16 transaction — within the usual Form 4 reporting window (timely).

Context

• This was a routine sell-to-cover tied to tax withholding for restricted stock units, which is common and does not necessarily indicate a change in insider sentiment. Purchases typically carry more weight when assessing insider conviction; this transaction appears administrative in nature.