BIIB
Biogen Inc. · Healthcare · Drug Manufacturers - General
Momentum inputs (comparable managers):
holder breadth +14.3% ·
share flow +5.4% ·
net new positions +12.5%
— formula
Broad accumulation — rising shares across more holders
All ownership figures: tracked 13F managers only, common-stock positions, reporting period Q3 2024
| Quarter | Holders | Δ | Shares | Reported value | New | Exits |
|---|---|---|---|---|---|---|
| Q2 2026 | 161 | 0 | 119.37M | $25.77B | +6 | −5 |
| Q1 2026 | 163 | -1 | 110.78M | $20.30B | +4 | −6 |
| Q4 2025 | 163 | 0 | 123.15M | $21.67B | +2 | −1 |
| Q3 2025 | 24 | +1 | 81.72M | $11.44B | +1 | −1 |
| Q2 2025 | 21 | 0 | 78.50M | $9.86B | — | — |
| Q1 2025 | 18 | +2 | 41.87M | $5.73B | +3 | −1 |
| Q4 2024 | 16 | -1 | 41.64M | $6.37B | — | −1 |
| Q3 2024 | 16 | +2 | 32.39M | $6.28B | +2 | — |
| Q2 2024 | 14 | — | 30.72M | $7.12B | — | — |
| # | Manager | Shares | Δ shares | Value | Their weight | Held | ||
|---|---|---|---|---|---|---|---|---|
| 1 | PRIMECAP Management ✦ | 16.32M | -0.1% | $3.16B | 2.3% | ▼ Trim | 2 | SEC ↗ |
| 2 | Wellington Management ✦ | 5.13M | -0.7% | $994.63M | 0.2% | ▼ Trim | 2 | SEC ↗ |
| 3 | Wellington Management ✦ | 5.13M | -0.7% | $994.63M | 0.2% | ▼ Trim | 2 | SEC ↗ |
| 4 | Wellington Management ✦ | 5.13M | -0.7% | $994.63M | 0.2% | ▼ Trim | 2 | SEC ↗ |
| 5 | Wellington Management ✦ | 5.13M | -0.7% | $994.63M | 0.2% | ▼ Trim | 2 | SEC ↗ |
| 6 | Wellington Management ✦ | 5.13M | -0.7% | $994.63M | 0.2% | ▼ Trim | 2 | SEC ↗ |
| 7 | Wellington Management ✦ | 5.13M | -0.7% | $994.63M | 0.2% | ▼ Trim | 2 | SEC ↗ |
| 8 | Wellington Management ✦ | 5.13M | -0.7% | $994.63M | 0.2% | ▼ Trim | 2 | SEC ↗ |
| 9 | Wellington Management ✦ | 5.13M | -0.7% | $994.63M | 0.2% | ▼ Trim | 2 | SEC ↗ |
| 10 | Geode Capital Management ✦ (passive) | 3.61M | +1.3% | $698.06M | 0.1% | ▲ Add | 2 | SEC ↗ |
| 11 | Geode Capital Management ✦ (passive) | 3.61M | +1.3% | $698.06M | 0.1% | ▲ Add | 2 | SEC ↗ |
| 12 | Norges Bank ✦ (passive) | 2.26M | +8.9% | $438.93M | 0.1% | ▲ Add | 2 | SEC ↗ |
| 13 | T. Rowe Price ✦ | 1.91M | -4.9% | $370.73M | 0.0% | ▼ Trim | 2 | SEC ↗ |
| 14 | T. Rowe Price ✦ | 1.91M | -4.9% | $370.73M | 0.0% | ▼ Trim | 2 | SEC ↗ |
| 15 | Renaissance Technologies ✦ | 952.71K | +54.1% | $184.67M | 0.3% | ▲ Add | 2 | SEC ↗ |
| 16 | Two Sigma Investments ✦ | 648.70K | +204.7% | $125.74M | 0.3% | ▲ Add | 2 | SEC ↗ |
| 17 | D. E. Shaw & Co. ✦ | 434.94K | +102.6% | $84.31M | 0.1% | ▲ Add | 2 | SEC ↗ |
| 18 | Millennium Management ✦ | 398.14K | +66.0% | $77.17M | 0.1% | ▲ Add | 2 | SEC ↗ |
| 19 | Citadel Advisors ✦ | 372.37K | New | $72.18M | 0.1% | New | 1 | SEC ↗ |
| 20 | Citadel Advisors ✦ | 372.37K | New | $72.18M | 0.1% | New | 1 | SEC ↗ |
| 21 | Bridgewater Associates ✦ | 72.10K | +339.2% | $13.98M | 0.1% | ▲ Add | 2 | SEC ↗ |
| 22 | Fisher Asset Management ✦ | 66.77K | -2.5% | $12.94M | 0.0% | ▼ Trim | 2 | SEC ↗ |
| 23 | Marshall Wace ✦ | 66.30K | New | $12.85M | 0.0% | New | 1 | SEC ↗ |
| 24 | Marshall Wace ✦ | 66.30K | New | $12.85M | 0.0% | New | 1 | SEC ↗ |
| 25 | AQR Capital Management ✦ | 49.88K | +111.8% | $9.62M | 0.0% | ▲ Add | 2 | SEC ↗ |
| 26 | AQR Capital Management ✦ | 49.88K | +111.8% | $9.62M | 0.0% | ▲ Add | 2 | SEC ↗ |
| 27 | AQR Capital Management ✦ | 49.88K | +111.8% | $9.62M | 0.0% | ▲ Add | 2 | SEC ↗ |
| 28 | Adage Capital Partners ✦ | 45.80K | -66.7% | $8.88M | 0.0% | ▼ Trim | 2 | SEC ↗ |
| 29 | Gotham Asset Management ✦ | 42.44K | +80.2% | $8.23M | 0.1% | ▲ Add | 2 | SEC ↗ |
“Their weight” = the position's share of that manager's reported 13F equity value — the conviction measure. ✦ = curated manager.
New buyers
| Citadel Advisors | $72.18M | 0.1% |
| Citadel Advisors | $72.18M | 0.1% |
| Marshall Wace | $12.85M | 0.0% |
| Marshall Wace | $12.85M | 0.0% |
Exited
| No tracked exits this quarter. |
Full-market context: across ALL 13F filers (SEC structured data, Q1 2026): 995 holders, 132.27M shares, $23.30B 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.