Allison Ambrose - 16 Mar 2026 Form 4 Insider Report for Upstream Bio, Inc. (UPB)

Role
General Counsel
Signature
/s/ Allison Ambrose
Issuer symbol
UPB
Transactions as of
16 Mar 2026
Net transactions value
-$4,413
Form type
4
Filing time
17 Mar 2026, 17:00:23 UTC
Previous filing
06 Jan 2026
SEC
View on sec.gov

Reporting Owners (1)

Name Relationship Address Signature Signature date CIK
Ambrose Allison General Counsel UPSTREAM BIO, INC., 890 WINTER STREET, SUITE 200, WALTHAM /s/ Allison Ambrose 17 Mar 2026 0002047381

Transactions Table

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Ownership Footnotes
transaction UPB Common Stock Sale $4,413 -475 -2.8% $9.29 16,525 16 Mar 2026 Direct F1
* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id Content
F1 The Issuer has adopted a "sell-to-cover" policy to satisfy the tax withholding obligations of the Reporting Person. The sales reported on this Form 4 represent the number of shares required to be sold by the Reporting Person to cover tax withholding obligations in connection with the vesting of restricted stock units. Such sales were automatic and not at the discretion of the Reporting Person.