Upstream Bio UPB Insider Ownership

NASDAQ UPB

$2.80 -0.02 (-0.71%)

At close: Oct 21, 2026 · 4:00 PM EDT

Insider Holdings by Owner

15.67Mn Shares

Insider Ownership Statistics

as of 30 Sep, 2026

Insider Ownership

20.29%

▼-0.0092% pp QoQ

Shares Held by Insiders

11.11Mn

filed for Sep 2026

▼-0.05% QoQ

Shares Outstanding

54.77Mn

54,771,041 shares

Direct Holdings

6.56Mn

Indirect: 4.55Mn

Net Shares Traded (QoQ)

-5.03K

net selling in Sep 2026

Insiders Holding Shares

with Form 4 holdings on file

Shares Owned by Insiders

Shares held % of outstanding

Latest —

Average ownership —

Peak ownership —

Shares Purchased/Sold by Insiders

Bought Sold

Latest quarter —

Net over range —

Buying quarters —

Insider Ownership Summary

Updated Oct 10, 2026

Over the past year, UPB insiders sold $104,796 of stock (15.06K shares) on the open market and bought none.

Behind Upstream Bio's open-market sales in the past 12 months were 5 insiders, and no insider bought.
The largest open-market sales of UPB in the past 12 months were by Everett Rand Sutherland (Chief Executive Officer), totaling $43,725 (6.28K shares), most recently on September 16, 2026.
Beyond open-market trades, insiders at Upstream Bio received 179.5K shares in stock awards in the last 12 months.
Business Quant data shows Upstream Bio insiders holding 11.11Mn shares in total in their latest Form 4 filings, or 20.29% of the 54.77Mn shares outstanding; that total is down 0.05% from 11.12Mn shares at the end of Q2 2026 and up 1.53% from 10.94Mn shares at the end of Q3 2025.
Of the 11.11Mn shares held by Upstream Bio insiders, 6.56Mn shares (59.01%) are held directly and 4.55Mn shares (40.99%) indirectly, through trusts, partnerships, family members and other entities.
Business Quant counts 8 insiders with holdings in Upstream Bio stock, among the officers, directors and 10% owners who have filed a Form 4 in the past two years.
UPB's largest insider holders by reported holdings are Ai Upstream LLC (10% owner, 5.49Mn shares), Erez Chimovits (Director and 10% owner, 4.55Mn shares) and Wellington Biomedical Innovation Master Investors (Cayman) II L.P. (10% owner, 894.73K shares).
Of the shares held by UPB insiders, 49.45% belong to Ai Upstream LLC.
In the last 12 months, 26 Form 4 filings with transactions in UPB stock came from 11 insiders.
The insider holdings and trades above for Upstream Bio reflect Form 4 filings through September 17, 2026.

Form 4 Holdings

Insiders Holding UPB

Insiders 9

Shares held 15.67Mn

Of outstanding 28.60%

#	Insider	Position	Direct	Indirect	Total	Share of Insiders	Last Filed
1	Upstream Llc Ai	TenPercentOwner	5,494,410	0	5,494,410	35.1%	17 Oct, 2024
2	Advisors Llc Orbimed	Director, TenPercentOwner	0	4,554,873	4,554,873	29.1%	17 Oct, 2024
3	Erez Chimovits	Director, TenPercentOwner	0	4,554,873	4,554,873	29.1%	17 Oct, 2024
4	Biomedical Innovation Master Investors (Cayman) Ii L.P. Wellington	TenPercentOwner	894,733	0	894,733	5.7%	15 Oct, 2024
5	Everett Rand Sutherland	Chief Executive Officer	68,717	0	68,717	0.4%	17 Sep, 2026
6	Aaron Deykin	Chief Medical Officer	32,302	0	32,302	0.2%	17 Sep, 2026
7	Michael Gray	Cfo And Coo	27,942	0	27,942	0.2%	17 Sep, 2026
8	Adam Houghton	Chief Business Officer	22,901	0	22,901	0.1%	17 Sep, 2026
9	Allison Ambrose	General Counsel	15,563	0	15,563	0.1%	17 Sep, 2026

Each row is that insider’s most recently reported position, from Form 4 filings over the last 60 months — which is why this total does not tie to the quarterly series above, where a quarter counts only the insiders who filed in it. Shares held through a fund or institutional portfolio are counted on the institutional ownership page instead.

Form 4 Filings

72 Insider Transactions

Source SEC Form 4

Latest quarter Sep 2026

Date	Insider	Position	Transaction	Shares	Price	Value	Shares Held After	Ownership
16 Sep, 2026	Everett Rand Sutherland	Chief Executive Officer	Disposed S	2,095	$5.49	$11.50K	68,717	Direct
16 Sep, 2026	Michael Gray	Cfo And Coo	Disposed S	853	$5.49	$4.68K	27,942	Direct
16 Sep, 2026	Allison Ambrose	General Counsel	Disposed S	485	$5.49	$2.66K	15,563	Direct
16 Sep, 2026	Adam Houghton	Chief Business Officer	Disposed S	700	$5.49	$3.84K	22,901	Direct
16 Sep, 2026	Aaron Deykin	Chief Medical Officer	Disposed S	895	$5.49	$4.91K	32,302	Direct
16 Jun, 2026	Michael Gray	Cfo And Coo	Disposed S	853	$6.10	$5.20K	28,795	Direct
16 Jun, 2026	Adam Houghton	Chief Business Officer	Disposed S	700	$6.10	$4.27K	23,601	Direct
16 Jun, 2026	Everett Rand Sutherland	Chief Executive Officer	Disposed S	2,095	$6.10	$12.78K	70,812	Direct
16 Jun, 2026	Aaron Deykin	Chief Medical Officer	Disposed S	895	$6.10	$5.46K	33,197	Direct
16 Jun, 2026	Allison Ambrose	General Counsel	Disposed S	477	$6.10	$2.91K	16,048	Direct
09 Jun, 2026	Ronald C Jr Renaud	Director	Acquired A	17,096	$0.00	$0	17,096	Direct
09 Jun, 2026	Harold Edward Fleming	Director	Acquired A	17,096	$0.00	$0	17,096	Direct
09 Jun, 2026	Liam Ratcliffe	Director	Acquired A	17,096	$0.00	$0	17,096	Direct
09 Jun, 2026	Erez Chimovits	Director	Acquired A	17,096	$0.00	$0	17,096	Direct
09 Jun, 2026	Marcella K. Ruddy	Director	Acquired A	17,096	$0.00	$0	17,096	Direct
09 Jun, 2026	Daniella Beckman	Director	Acquired A	17,096	$0.00	$0	17,096	Direct
16 Mar, 2026	Aaron Deykin	Chief Medical Officer	Disposed S	894	$9.29	$8.31K	32,687	Direct
16 Mar, 2026	Adam Houghton	Chief Business Officer	Disposed S	699	$9.29	$6.49K	24,301	Direct
16 Mar, 2026	Everett Rand Sutherland	Chief Executive Officer	Disposed S	2,093	$9.29	$19.44K	72,907	Direct
16 Mar, 2026	Michael Gray	Cfo And Coo	Disposed S	852	$9.29	$7.92K	29,648	Direct

Showing 1 to 20 of 72 transactions