Institutional ownership · Form 13F
BIIB institutional ownership
Biogen: reported institutional holdings as of 2026-06-30 (filed through 2026-08-31), aggregated by StockEyes from SEC Form 13F information tables. BIIB 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%.
BIIB: change since the prior quarter's filings
More managers reported a position, with the count rising from 995 in the quarter ended 2026-03-31 to 1,042 in the quarter ended 2026-06-30 (+47, 4.7%). Total reported shares rose to 142,254,095 (+7,998,151, 6.0%), moving the same way as the manager count. Among the 28 managers listed as top holders in both quarters, the largest increases were FMR LLC (+5,409,698 shares) and Amundi (+726,004 shares), among 19 managers who added shares, and the largest decreases were Boston Partners (-436,649 shares) and JPMORGAN CHASE & CO (-192,869 shares), among 9 managers who reduced shares. NORGES BANK (2,580,033 shares) and UBS Group AG (1,030,150 shares) entered the listed top holders; Point72 Asset Management, L.P. (809,617 shares in the prior quarter) and MASSACHUSETTS FINANCIAL SERVICES CO /MA/ (720,629 shares in the prior quarter) 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
1,042 reporting managers held 142,254,095 shares, reported value $29,822,917,354 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 +47, reported shares +7,998,151 (+5.96%), reported value +25.93%. These changes compare two filing snapshots.
Shares outstanding check: 146,800,000 shares reported by the issuer (SEC XBRL, period ended 2025-12-31). Reported 13F shares equal 96.9% of that figure. This page passed the publication sanity gate before listing.
BIIB in this quarter's filings
Concentration check: the largest reported position, FMR LLC with 18,217,239 shares, is 12.8% of all shares reported for BIIB this quarter. The five largest reporting managers together account for 46.6% 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 47 versus the quarter ended 2026-03-31, and reported shares moved +5.96% (+7,998,151 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 96.9% of the issuer share count used at the publication gate (146,800,000 shares, issuer period ended 2025-12-31). 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, BIIB
| # | Manager | Shares | Value as filed | Share of reported total |
|---|---|---|---|---|
| 1 | FMR LLC | 18,217,239 | $3,936,016,552 | 12.8% |
| 2 | BlackRock, Inc. | 15,985,736 | $3,453,877,982 | 11.2% |
| 3 | PRIMECAP MANAGEMENT CO/CA/ | 15,154,606 | $3,274,304,389 | 10.7% |
| 4 | VANGUARD CAPITAL MANAGEMENT LLC | 9,651,117 | $2,085,220,339 | 6.8% |
| 5 | STATE STREET CORP | 7,344,327 | $1,586,815,292 | 5.2% |
| 6 | VANGUARD PORTFOLIO MANAGEMENT LLC | 6,604,936 | $1,427,062,472 | 4.6% |
| 7 | GEODE CAPITAL MANAGEMENT, LLC | 4,449,295 | $957,935,835 | 3.1% |
| 8 | WELLINGTON MANAGEMENT GROUP LLP | 3,117,469 | $673,560,352 | 2.2% |
| 9 | NORGES BANK | 2,580,033 | $557,441,930 | 1.8% |
| 10 | MORGAN STANLEY | 2,411,271 | $520,979,947 | 1.7% |
| 11 | AQR CAPITAL MANAGEMENT LLC | 1,936,859 | $416,928,075 | 1.4% |
| 12 | JPMORGAN CHASE & CO | 1,823,140 | $394,947,245 | 1.3% |
| 13 | Invesco Ltd. | 1,803,944 | $389,760,120 | 1.3% |
| 14 | Amundi | 1,516,831 | $327,726,507 | 1.1% |
| 15 | Legal & General Group Plc | 1,493,289 | $322,640,021 | 1.0% |
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 | 995 | 134,255,944 | $23,681,609,206 |
| 2026-06-30 | 2026-08-31 | 1,042 | 142,254,095 | $29,822,917,354 |
Every change figure on this page is a reported quarter-over-quarter change between filing snapshots. It is not real-time trading activity.
BIIB reported totals over time
Quarter ended 2026-06-30: 1,042 reporting managers · 142,254,095 reported shares · $29,822,917,354 value as filed.
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Quarter-end 13F filed data, long positions only; filings arrive up to 45 days after quarter end.
CUSIPs behind the BIIB total
The validated bridge mapped 1 current CUSIP(s) to BIIB for this quarter: 09062X103. 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 BIIB (officer and director buys and sells) are covered by InsiderTrace: insidertrace.com/stock/biib. StockEyes does not duplicate insider transaction tables.
Related StockEyes pages
Latest headlines tagged BIIB 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.