Deykin Aaron 4

What Happened

• Aaron Deykin, Chief Medical Officer of Upstream Bio (UPB), disposed of 895 shares on June 16, 2026. The shares were sold at $6.10 each for a total proceeds of $5,460. This transaction is reported as a sale (routine sell-to-cover) rather than a purchase or strategic disposition.

Key Details

• Transaction date and price: 2026-06-16 — sale of 895 shares at $6.10 per share (total $5,460).
• Transaction type/code: Sale (S). Footnote F1 indicates this was an automatic "sell-to-cover" to satisfy tax withholding connected to RSU vesting.
• Shares owned after transaction: Not specified in the provided summary; Form 4 notes (F2) that 1,405 shares were previously acquired under the 2024 Employee Stock Purchase Plan.
• Filing timeliness: Report filed 2026-06-17 for a 2026-06-16 transaction — appears timely.
• Footnotes: F1 = automatic sale to cover tax withholding for vested restricted stock units; F2 = includes 1,405 shares acquired under the 2024 ESPP.

Context

• Sell-to-cover transactions are routine administrative sales tied to tax withholding when restricted stock units vest and do not necessarily indicate a change in the insider’s view of the company. The small size ($5.5k) here suggests it was purely to meet withholding obligations.