Upstream Bio, Inc. (UPB) Insider Ownership

Historic Insider Ownership Trends

UPB's three largest insider shareholders as of March 23, 2026 are Erez Chimovits (Director, 4.55Mn shares), Biomedical Innovation Master Investors (Cayman) Ii L.P. Wellington (TenPercentOwner, 894.73K shares), Everett Rand Sutherland (Chief Executive Officer, 75.00K shares).

Top Direct Holders

Insider ownership data is derived from the last 60 months of Form 4 SEC filings.
Holder Position Shares (Direct) Shares (Indirect) Report Date
Erez Chimovits 0 4,554,873 17 Oct, 2024
Biomedical Innovation Master Investors (Cayman) Ii L.P. Wellington 894,733 0 15 Oct, 2024
Everett Rand Sutherland Chief Executive Officer 75,000 0 06 Jan, 2026
Everett Rand Sutherland Chief Executive Officer 72,907 0 17 Mar, 2026
Aaron Deykin Chief Medical Officer 33,581 0 06 Jan, 2026
Aaron Deykin Chief Medical Officer 32,687 0 17 Mar, 2026
Michael Gray Cfo And Coo 29,648 0 17 Mar, 2026
Adam Houghton Chief Business Officer 25,000 0 06 Jan, 2026
Adam Houghton Chief Business Officer 24,301 0 17 Mar, 2026
Allison Ambrose General Counsel 17,000 0 06 Jan, 2026
Allison Ambrose General Counsel 16,525 0 17 Mar, 2026

* Please note that the shares above only reflect shares from the fund portfolio and the institutional portfolio. Shares from the personal portfolio are excluded from this Institutional Ownership Page. See these insiders' latest transactions here on Insider Page.

Recent Insider Transactions

Detailed insider trading activity based on Form 4 SEC filings.
Download Data
Transaction Date Insider Name Security Class Transaction Type Shares Traded Price Shares Remaining Ownership Code
16 Mar, 2026 Adam Houghton Common Stock D 699 $9.29 24,301 D S
16 Mar, 2026 Aaron Deykin Common Stock D 894 $9.29 32,687 D S
16 Mar, 2026 Allison Ambrose Common Stock D 475 $9.29 16,525 D S
16 Mar, 2026 Everett Rand Sutherland Common Stock D 2,093 $9.29 72,907 D S
16 Mar, 2026 Michael Gray Common Stock D 852 $9.29 29,648 D S
02 Jan, 2026 Allison Ambrose Common Stock A 17,000 $0.00 17,000 D A
02 Jan, 2026 Adam Houghton Common Stock A 25,000 $0.00 25,000 D A
02 Jan, 2026 Aaron Deykin Common Stock A 32,000 $0.00 33,581 D A
02 Jan, 2026 Aaron Deykin Common Stock A 32,000 $0.00 33,581 D A
02 Jan, 2026 Everett Rand Sutherland Common Stock A 75,000 $0.00 75,000 D A
02 Jan, 2026 Adam Houghton Common Stock A 25,000 $0.00 25,000 D A
02 Jan, 2026 Everett Rand Sutherland Common Stock A 75,000 $0.00 75,000 D A
02 Jan, 2026 Allison Ambrose Common Stock A 17,000 $0.00 17,000 D A
02 Jan, 2026 Michael Gray Common Stock A 30,500 $0.00 30,500 D A
02 Jan, 2026 Adam Houghton Stock Option (Right to Buy) A 75,000 $0.00 75,000 D A
02 Jan, 2026 Allison Ambrose Stock Option (Right to Buy) A 51,000 $0.00 51,000 D A
02 Jan, 2026 Michael Gray Stock Option (Right to Buy) A 91,500 $0.00 91,500 D A
02 Jan, 2026 Aaron Deykin Stock Option (Right to Buy) A 96,000 $0.00 96,000 D A
02 Jan, 2026 Everett Rand Sutherland Stock Option (Right to Buy) A 225,000 $0.00 225,000 D A
02 Jan, 2026 Adam Houghton Stock Option (Right to Buy) A 75,000 $0.00 75,000 D A