UPB
Upstream Bio, Inc. · Healthcare · Biotechnology
Momentum inputs (comparable managers):
holder breadth +14.3% ·
share flow -8.5% ·
net new positions +12.5%
— formula
Ownership fragmentation — more holders, smaller aggregate stake
All ownership figures: tracked 13F managers only, common-stock positions, reporting period Q1 2025
| Quarter | Holders | Δ | Shares | Reported value | New | Exits |
|---|---|---|---|---|---|---|
| Q2 2026 | 66 | +3 | 29.87M | $206.85M | +14 | −10 |
| Q1 2026 | 64 | +3 | 24.32M | $219.33M | +14 | −12 |
| Q4 2025 | 62 | +3 | 27.51M | $746.80M | +4 | — |
| Q3 2025 | 14 | +2 | 17.53M | $329.70M | +2 | −1 |
| Q2 2025 | 10 | -1 | 15.87M | $174.20M | +1 | −2 |
| Q1 2025 | 8 | +1 | 3.40M | $20.78M | +3 | −2 |
| Q4 2024 | 7 | +6 | 3.71M | $60.61M | +6 | — |
| # | Manager | Shares | Δ shares | Value | Their weight | Held | ||
|---|---|---|---|---|---|---|---|---|
| 1 | Wellington Management ✦ | 1.31M | -17.0% | $8.03M | 0.0% | ▼ Trim | 2 | SEC ↗ |
| 2 | Wellington Management ✦ | 1.31M | -17.0% | $8.03M | 0.0% | ▼ Trim | 2 | SEC ↗ |
| 3 | Wellington Management ✦ | 1.31M | -17.0% | $8.03M | 0.0% | ▼ Trim | 2 | SEC ↗ |
| 4 | Norges Bank ✦ (passive) | 969.92K | -3.0% | $5.94M | 0.0% | ▼ Trim | 2 | SEC ↗ |
| 5 | Geode Capital Management ✦ (passive) | 410.68K | +13.1% | $2.51M | 0.0% | ▲ Add | 2 | SEC ↗ |
| 6 | Geode Capital Management ✦ (passive) | 410.68K | +13.1% | $2.51M | 0.0% | ▲ Add | 2 | SEC ↗ |
| 7 | Marshall Wace ✦ | 304.96K | +4.9% | $1.87M | 0.0% | ▲ Add | 2 | SEC ↗ |
| 8 | Marshall Wace ✦ | 304.96K | +4.9% | $1.87M | 0.0% | ▲ Add | 2 | SEC ↗ |
| 9 | State Street Global Advisors ✦ (passive) | 295.59K | +19.6% | $1.81M | 0.0% | ▲ Add | 2 | SEC ↗ |
| 10 | Millennium Management ✦ | 61.80K | New | $378,192 | 0.0% | New | 1 | SEC ↗ |
| 11 | Two Sigma Investments ✦ | 21.79K | New | $133,349 | 0.0% | New | 1 | SEC ↗ |
| 12 | AQR Capital Management ✦ | 18.82K | New | $115,190 | 0.0% | New | 1 | SEC ↗ |
| 13 | AQR Capital Management ✦ | 18.82K | New | $115,190 | 0.0% | New | 1 | SEC ↗ |
| 14 | AQR Capital Management ✦ | 18.82K | New | $115,190 | 0.0% | New | 1 | SEC ↗ |
| 15 | AQR Capital Management ✦ | 18.82K | New | $115,190 | 0.0% | New | 1 | SEC ↗ |
| 16 | AQR Capital Management ✦ | 18.82K | New | $115,190 | 0.0% | New | 1 | SEC ↗ |
“Their weight” = the position's share of that manager's reported 13F equity value — the conviction measure. ✦ = curated manager.
New buyers
| Millennium Management | $378,192 | 0.0% |
| Two Sigma Investments | $133,349 | 0.0% |
| AQR Capital Management | $115,190 | 0.0% |
| AQR Capital Management | $115,190 | 0.0% |
| AQR Capital Management | $115,190 | 0.0% |
| AQR Capital Management | $115,190 | 0.0% |
| AQR Capital Management | $115,190 | 0.0% |
Exited
| Citadel Advisors | $2.96M | was 0.0% |
| Soros Fund Management | $761,994 | was 0.0% |
Full-market context: across ALL 13F filers (SEC structured data, Q1 2026): 140 holders, 44.42M shares, $399.81M reported. This is a different, older period than the tracked-universe figures above and the two are never mixed.
What else this security's tracked holders most often hold — shared-ownership counts, not fundamental relationships.