Upstream Bio, Inc. (UPB) Ownership
UPB ownership summary
as of October 18, 2026- Institutions
- 92.3% of shares outstanding
- Insiders
- 14.78% of shares outstanding
- Shares outstanding
- 54.8M
- Float
- 42.8M shares available to trade
- Short interest
- 12.67% 4.5M shares short
- Days to cover
- 7.05 short interest up 0.5% vs prior month
- Institutions 92.35%
- Insiders 14.78%
UPB top institutional holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | FMR Inc | 14.90% | 8.2M | $22.5M | +61,334 (+0.8%) | June 30, 2026 |
| 2 | Orbimed Advisors LLC | 10.40% | 5.7M | $15.7M | — | June 30, 2026 |
| 3 | NORGES BANK | 6.88% | 3.8M | $10.4M | +885,972 (+30.7%) | June 30, 2026 |
| 4 | BlackRock Inc | 6.85% | 3.8M | $10.4M | +382,669 (+11.4%) | June 30, 2026 |
| 5 | Decheng Capital LLC | 4.97% | 2.7M | $7.5M | — | June 30, 2026 |
| 6 | Enavate Sciences GP, LLC | 4.49% | 2.5M | $6.8M | — | June 30, 2026 |
| 7 | Vanguard Capital Management, LLC | 3.43% | 1.9M | $5.2M | +3,160 (+0.2%) | June 30, 2026 |
| 8 | Millennium Management LLC | 2.09% | 1.1M | $3.2M | +206,452 (+22.0%) | June 30, 2026 |
| 9 | D. E. Shaw & Co LP | 1.89% | 1.0M | $2.9M | +215,564 (+26.3%) | June 30, 2026 |
| 10 | JPMorgan Chase & Co | 1.85% | 1.0M | $2.8M | +549,043 (+118.6%) | June 30, 2026 |
| 11 | Qube Research & Technologies | 1.79% | 978K | $2.7M | +359,179 (+58.0%) | June 30, 2026 |
| 12 | Parkman Healthcare Partners LLC | 1.71% | 935K | $2.6M | +148,464 (+18.9%) | June 30, 2026 |
| 13 | Geode Capital Management, LLC | 1.70% | 931K | $2.6M | −19,356 (−2.0%) | June 30, 2026 |
| 14 | SEB Asset Management AB | 1.60% | 878K | $2.4M | — | June 30, 2026 |
| 15 | Woodline Partners LP | 1.52% | 831K | $2.3M | — | June 30, 2026 |
| 16 | State Street Corp | 1.40% | 766K | $2.1M | +60,973 (+8.6%) | June 30, 2026 |
| 17 | Vanguard Portfolio Management, LLC | 1.30% | 713K | $2.0M | −15,044 (−2.1%) | June 30, 2026 |
| 18 | Y-Intercept (Hong Kong) Ltd | 1.27% | 694K | $1.9M | −307,076 (−30.7%) | June 30, 2026 |
| 19 | Bain Capital Life Sciences Investors, LLC | 1.10% | 601K | $1.7M | −266,262 (−30.7%) | June 30, 2026 |
| 20 | AQR Capital Management LLC | 0.99% | 545K | $1.5M | +472,698 (+655.0%) | June 30, 2026 |
Value at the latest close. Change = shares bought or sold in the latest quarterly filing (13F). In the top 20, 11 holders added 3.3M shares and 4 cut 608K.
UPB top mutual fund and ETF holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | Vanguard MStar Total Stk Mkt Idx Invest | 2.63% | 1.4M | $4.0M | — | August 31, 2026 |
| 2 | Fidelity Small Cap Growth | 2.50% | 1.4M | $3.8M | — | July 31, 2026 |
| 3 | Fidelity Stock Selector Small Cap | 2.41% | 1.3M | $3.6M | — | July 31, 2026 |
| 4 | Fidelity Series Small Cap Opps | 1.76% | 966K | $2.7M | — | July 31, 2026 |
| 5 | iShares Russell 2000 ETF | 1.69% | 926K | $2.6M | −10,688 (−1.1%) | September 30, 2026 |
| 6 | SEB Läkemedelsfond A (SEK) | 1.60% | 878K | $2.4M | — | August 31, 2026 |
| 7 | Fidelity Select Health Care | 1.46% | 800K | $2.2M | — | August 31, 2026 |
| 8 | Fidelity Small Cap Growth K6 | 1.27% | 694K | $1.9M | — | July 31, 2026 |
| 9 | Fidelity Advisor Biotechnology I | 1.26% | 691K | $1.9M | — | August 31, 2026 |
| 10 | Fidelity Advisor Health Care I | 0.73% | 400K | $1.1M | — | August 31, 2026 |
| 11 | Fidelity Small Cap Index | 0.70% | 385K | $1.1M | +1,693 (+0.4%) | July 31, 2026 |
| 12 | iShares Russell 2000 Value ETF | 0.67% | 367K | $1.0M | +556 (+0.2%) | September 30, 2026 |
| 13 | Strategic Advisers Fidelity US TtlStk | 0.61% | 336K | $928,078 | +199,700 (+146.2%) | August 31, 2026 |
| 14 | iShares Biotechnology ETF | 0.52% | 283K | $780,887 | −2,144 (−0.8%) | September 30, 2026 |
| 15 | Fidelity Select Biotechnology | 0.43% | 235K | $647,653 | — | August 31, 2026 |
| 16 | Vanguard Strategic Small-Cap Equity Inv | 0.43% | 235K | $647,593 | +137,333 (+141.1%) | June 30, 2026 |
| 17 | BGF World Healthscience A2 | 0.43% | 233K | $643,947 | — | June 30, 2026 |
| 18 | Schwab US Small-Cap ETF™ | 0.38% | 208K | $575,259 | +135 (+0.1%) | September 30, 2026 |
| 19 | DWS ESG Biotech LC | 0.38% | 208K | $575,250 | — | August 31, 2026 |
| 20 | Vanguard Russell 2000 ETF | 0.37% | 202K | $558,307 | +3,960 (+2.0%) | August 31, 2026 |
Funds report holdings monthly or quarterly; dates differ by fund.
UPB insider transactions
latest 1| Date | Name | Transaction | Price | Shares | Value |
|---|---|---|---|---|---|
| 2026-03-16 | Michael Gray | Sell | $9.29 | 852 | $7,915 |
Reported trades by company officers, directors and other filers (including disclosures by members of Congress where EODHD lists them). "—" where the filing gives no share count.
UPB shares outstanding
Year-end shares outstanding, adjusted for splits.
Who owns UPB
Institutional investors own 92.3% of Upstream Bio's shares and insiders 14.78%. The largest holder is FMR Inc with 14.90% of the shares (8.2M), as of June 30, 2026. Among the top 20 institutions, 11 added shares and 4 reduced their stake in the latest filings. Short interest is 12.67% of the float, or 7.05 days of average trading volume. The share count rose 49.3% since 2023.
Related: UPB analyst forecast, UPB key metrics. See the UPB stock overview for the latest quote and news.
UPB ownership FAQ
Who owns the most Upstream Bio stock?
The largest shareholders of Upstream Bio are FMR Inc (14.90%), Orbimed Advisors LLC (10.40%), NORGES BANK (6.88%), BlackRock Inc (6.85%), Decheng Capital LLC (4.97%).
What percentage of Upstream Bio is owned by institutions?
Institutions hold 92.3% of Upstream Bio's shares outstanding; insiders hold 14.78%.
Which funds own Upstream Bio?
The largest fund holders of Upstream Bio are Vanguard MStar Total Stk Mkt Idx Invest (2.63%), Fidelity Small Cap Growth (2.50%), Fidelity Stock Selector Small Cap (2.41%), Fidelity Series Small Cap Opps (1.76%), iShares Russell 2000 ETF (1.69%).
What is Upstream Bio's short interest?
4.5M shares of Upstream Bio were sold short, 12.67% of the float; at the average daily volume it would take 7.05 days to cover.
Are insiders buying or selling Upstream Bio?
Of the latest 1 reported insider transactions in Upstream Bio (since March 16, 2026), 0 were purchases and 1 were sales.
How many shares of Upstream Bio are outstanding?
Upstream Bio has 54.8M shares outstanding, of which 42.8M are in the public float.