Institutional ownership · Form 13F
UPB institutional ownership
Upstream Bio, Inc. - Common Stock: reported institutional holdings as of 2026-06-30 (filed through 2026-08-31), aggregated by StockEyes from SEC Form 13F information tables. UPB is one of 2732 tickers in the validated publication set. Mapping coverage in this publication set: 4562 of 6046 universe tickers have at least one validated CUSIP mapping (75.5%). Latest-quarter filed value resolved to any listed ticker: 77.3%; resolved to this universe: 77.2%.
UPB: change since the prior quarter's filings
More managers reported a position, with the count rising from 141 in the quarter ended 2026-03-31 to 149 in the quarter ended 2026-06-30 (+8, 5.7%). Total reported shares rose to 50,573,705 (+5,687,191, 12.7%), moving the same way as the manager count. Among the 21 managers listed as top holders in both quarters, the largest increases were JPMORGAN CHASE & CO (+549,043 shares) and BlackRock, Inc. (+382,669 shares), among 9 managers who added shares, and the largest decreases were SAMSARA BIOCAPITAL, LLC (-382,330 shares) and Y-Intercept (Hong Kong) Ltd (-307,076 shares), among 6 managers who reduced shares. NORGES BANK (3,768,619 shares), AQR CAPITAL MANAGEMENT LLC (544,869 shares) and 7 more entered the listed top holders; FEDERATED HERMES, INC. (979,758 shares in the prior quarter), Pictet Asset Management Holding SA (733,431 shares in the prior quarter) and 7 more dropped out of the listed top holders.
New to 13F data? Read how to read a 13F filing, or see where institutions moved overall in the Smart Money Report.
Reported totals, quarter ended 2026-06-30
149 reporting managers held 50,573,705 shares, reported value $346,893,623 exactly as filed. Values are position values transcribed from the filings, not current market prices.
Reported quarter-over-quarter change (quarter ended 2026-03-31 to quarter ended 2026-06-30): reporting managers +8, reported shares +5,687,191 (+12.67%), reported value -14.11%. These changes compare two filing snapshots.
Shares outstanding check: 54,567,976 shares reported by the issuer (SEC XBRL, period ended 2026-06-30). Reported 13F shares equal 92.7% of that figure. This page passed the publication sanity gate before listing.
UPB in this quarter's filings
Concentration check: the largest reported position, FMR LLC with 8,162,897 shares, is 16.1% of all shares reported for UPB this quarter. The five largest reporting managers together account for 47.7% of the reported total, so the headline total is spread across a broad manager base rather than a few holders.
Reported quarter-over-quarter change: the reporting-manager count rose by 8 versus the quarter ended 2026-03-31, and reported shares moved +12.67% (+5,687,191 shares). That is a comparison of two filing snapshots, not a record of trades on any single day.
Shares-outstanding cross-check: reported 13F shares equal 92.7% of the issuer share count used at the publication gate (54,567,976 shares, issuer period ended 2026-06-30). The gate publishes a ticker only when that relationship is plausible; lending chains can push reported totals above a simple ownership share, which is why the figure is a sanity check and not an ownership percentage.
Largest reporting managers, UPB
| # | Manager | Shares | Value as filed | Share of reported total |
|---|---|---|---|---|
| 1 | FMR LLC | 8,162,897 | $56,487,247 | 16.1% |
| 2 | ORBIMED ADVISORS LLC | 5,693,589 | $39,399,636 | 11.3% |
| 3 | NORGES BANK | 3,768,619 | $26,078,843 | 7.5% |
| 4 | BlackRock, Inc. | 3,753,358 | $25,973,237 | 7.4% |
| 5 | Decheng Capital LLC | 2,724,868 | $18,856,087 | 5.4% |
| 6 | ENAVATE SCIENCES GP, LLC | 2,459,703 | $17,021,145 | 4.9% |
| 7 | VANGUARD CAPITAL MANAGEMENT LLC | 1,876,734 | $12,986,999 | 3.7% |
| 8 | MILLENNIUM MANAGEMENT LLC | 1,143,775 | $7,914,923 | 2.3% |
| 9 | D. E. Shaw & Co., Inc. | 1,036,044 | $7,169,425 | 2.0% |
| 10 | JPMORGAN CHASE & CO | 1,012,044 | $7,013,464 | 2.0% |
| 11 | Qube Research & Technologies Ltd | 978,500 | $6,771,220 | 1.9% |
| 12 | Parkman Healthcare Partners LLC | 935,247 | $6,471,909 | 1.8% |
| 13 | GEODE CAPITAL MANAGEMENT, LLC | 931,261 | $6,445,888 | 1.8% |
| 14 | SEB Asset Management AB | 878,473 | $6,079,022 | 1.7% |
| 15 | Woodline Partners LP | 831,481 | $5,753,849 | 1.6% |
Manager names and figures are transcribed from each manager's own Form 13F information table. A manager listing shares in this snapshot does not mean it holds them today.
Reported change, 2026-03-31 to 2026-06-30
| Quarter ended | Filed through | Reporting managers | Reported shares | Value as filed |
|---|---|---|---|---|
| 2026-03-31 | 2026-05-29 | 141 | 44,886,514 | $403,874,675 |
| 2026-06-30 | 2026-08-31 | 149 | 50,573,705 | $346,893,623 |
Every change figure on this page is a reported quarter-over-quarter change between filing snapshots. It is not real-time trading activity.
UPB reported totals over time
Quarter ended 2026-06-30: 149 reporting managers · 50,573,705 reported shares · $346,893,623 value as filed.
The full archived series is part of StockEyes Pro. Continue with Google to sign in.
Quarter-end 13F filed data, long positions only; filings arrive up to 45 days after quarter end.
CUSIPs behind the UPB total
The validated bridge mapped 1 current CUSIP(s) to UPB for this quarter: 91678A107. Option pseudo-CUSIPs, units, warrants, and preferred classes are excluded from these common-share totals. Mapping coverage in this publication set: 4562 of 6046 universe tickers have at least one validated CUSIP mapping (75.5%). Latest-quarter filed value resolved to any listed ticker: 77.3%; resolved to this universe: 77.2%.
What this page is and is not
Form 13F reports are quarterly holdings snapshots. Managers file up to about 45 days after quarter-end, so these figures describe reported positions as of the quarter-end date, not holdings today. 13F lists reportable long positions from managers above the SEC reporting threshold and omits short positions entirely.
This page is informational only. It is not investment advice, a recommendation, or a signal to buy or sell. Source: SEC Form 13F bulk data set for filings through 2026-08-31 (period ended 2026-06-30), joined to tickers through StockEyes' validated CUSIP bridge. Methodology and coverage are documented on the institutional ownership hub.
Insider transactions for UPB (officer and director buys and sells) are covered by InsiderTrace: insidertrace.com/stock/upb. StockEyes does not duplicate insider transaction tables.
Related StockEyes pages
Latest headlines tagged UPB are on the market news wire. Upcoming earnings and market dates are on the events calendar. The term itself is defined in the institutional investor glossary entry, and the research workflow behind pages like this one is walked through in how to research a stock and how to compare SEC filings.