Who owns Biogen Inc (BIIB)?
391 US mutual funds and ETFs from 171 fund families reported a position in BIIB for the quarter ending 2026-06-30. Against their own report a quarter earlier, 124 raised shares, 33 opened a new position, 144 cut and 42 sold out.
Largest fund families
| Fund family | Funds | Share of fund-held shares |
|---|---|---|
| Vanguard Index Funds | 6 | 30.0% |
| Vanguard Chester Funds | 1 | 17.6% |
| Fidelity Contrafund | 4 | 13.1% |
| Ishares Trust | 14 | 10.6% |
| Vanguard Horizon Funds | 1 | 5.5% |
| Vanguard Fenway Funds | 1 | 2.8% |
Tracked managers holding BIIB
None of the managers Prior Moves tracks on 13F reports BIIB in its latest filing.
Source: SEC Form N-PORT, which funds file about 60 days after quarter end, and the latest 13F filings. Share counts, not trades: a change can reflect fund inflows or outflows rather than a decision about BIIB. A record of holdings, not a forecast and not investment advice. See all owner pages or the forecast board for the names our model ranks.
Our model ranks every tracked manager’s likely next buys from 13F filings. Request the dataset sample with a work email.
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