Harold Edward Fleming - 09 Jun 2026 Form 4 Insider Report for Upstream Bio, Inc. (UPB)

Reporting relationship: Director
Issuer ticker: UPB
Reported as of: 09 Jun 2026
Net transaction value: $0
SEC form: 4
Accepted by SEC: 11 Jun 2026, 20:00:08 UTC
Prior SEC filing: 09 Jun 2026
Next SEC filing: 18 Jun 2026
Source filing: View source filing
Reporting owner signature: /s/ Allison Ambrose, Attorney-in-Fact

Key filing fact

Harold Edward Fleming filed Form 4 for Upstream Bio, Inc. (UPB) on 11 Jun 2026.

Key facts

This page summarizes Harold Edward Fleming's Form 4 filing for Upstream Bio, Inc. (UPB).
1 reported transaction and 1 derivative row are listed below.
Accepted by SEC: 11 Jun 2026, 20:00.

Change

Previous filing in this sequence was filed on 09 Jun 2026.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001857250 Primary reporting owner

Fleming Harold Edward

Relationship: Director
Address: UPSTREAM BIO, INC., 890 WINTER STREET, SUITE 200, WALTHAM
Signature: /s/ Allison Ambrose, Attorney-in-Fact
Signature date: 11 Jun 2026

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

UPB transaction Derivative

Stock Option (Right to Buy)

Award

Transaction value
Shares: +17,096
Change %
Price: $0.000000^*
Shares after: 17,096
Date: 09 Jun 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 17,096
Exercise price: $6.69
Footnotes: F1, F2

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 2 footnotes

Footnote F1

The shares underlying this option shall vest in full upon the earlier of (i) June 9, 2027 and (ii) the date of the next Annual Meeting of Stockholders of the Issuer, subject to the Reporting Person's continued service on such vesting date.

Footnote F2

Mr. Fleming has agreed to receive and hold for the benefit of Enavate Sciences, LP, any securities granted to him for his service as a director on the Issuer's board of directors. As such, Mr. Fleming disclaims beneficial ownership of, and all right, title and interest in, the option and the shares issuable upon exercise thereof.