What does CUSIP 09062X103 represent in this 13F holders report?

CUSIP 09062X103 is the security identifier for BIIB - BIOGEN INC. - COMMON STOCK used to aggregate holder disclosures.

How many institutions held BIIB - BIOGEN INC. - COMMON STOCK in Q1 2026?

1003 institutional investors reported BIIB - BIOGEN INC. - COMMON STOCK for Q1 2026. Use the holders table for investor-level position and value details.

BIOGEN INC. - COMMON STOCK (BIIB)

CUSIP: 09062X103

Q1 2026 13F Holders as of 31 Mar 2026

Security type / class: Equity / COMMON STOCK
Total 13F shares: 134,906,238
Total 13F value: $24,725,883,208
Share change: -4,901,661
Put/Call ratio: 133%
SEC-reported price per share: $183.33
Number of holders: 1,003
Value change: -$863,889,583
Number of buys: 510
Number of sells: 394
Shares outstanding: 147,371,459

Security key

09062X103

Report period

Q1 2026

Institutions

1,003

Top holders

BIIB full security history Ownership snapshot Full 13F holder table BIOGEN INC. SEC filings BIOGEN INC. company facts BIOGEN INC. 13D/G history

Broader feeds

Latest 13F filings Latest 13D/G filings Investors directory

Ownership snapshot

Top reported holders of BIIB - BIOGEN INC. - COMMON STOCK (13F + 13D/G + 3/4/5)

Grouped by holder across the latest SEC ownership disclosures. Start with comparable ownership when available, then verify the linked 13F, 13D/G, or 3/4/5 evidence.

Comparable stake leader

PRIMECAP MANAGEMENT CO/CA/

Disclosed value leader

VANGUARD GROUP INC

Comparable rows

15/15

Latest evidence

31 Mar 2026

13F 13D/G 3/4/5 Lead comparable stake: 10% 13D/G row: PRIMECAP MANAGEMENT CO/CA/ Showing 1-6 of 15 holder rows.

Quick read

PRIMECAP MANAGEMENT CO/CA/ leads the comparable SEC ownership view at 10%.

15 of 15 rows have a safely comparable ownership percentage. Use this as a filing-backed starting point, then open the detailed table for source links, reporting role, position value, share count, and filing date.

Open SEC evidence Opens PRIMECAP MANAGEMENT CO/CA/'s linked filing trail.

Comparable ownership Top 5

PRIMECAP MANAGEMENT CO/CA/ 10%

BlackRock, Inc. 8.5%

VANGUARD CAPITAL MANAGEMENT LLC 7.5%

STATE STREET CORP 5%

Caroline Dorsa 0.02%

Ownership % is shown only when SEC disclosures are safely comparable across share classes.

Detailed SEC evidence table Showing 1-6 of 15 holder rows

Holder	Evidence	Ownership %	Position	12M Net Δ	As of
PRIMECAP MANAGEMENT CO/CA/	13F 13D/G Company 13F 13D/G	10% from 13D/G	$2,597,259,895 14,757,997 shares	—	31 Dec 2025
BlackRock, Inc.	13F 13D/G Company 13F 13D/G	8.5% from 13D/G	$2,606,652,919 14,811,370 shares	—	31 Dec 2025
VANGUARD CAPITAL MANAGEMENT LLC	13D/G Vanguard Capital Management 13D/G	7.5%	$2,014,716,401 10,989,562 shares	$0	31 Mar 2026
STATE STREET CORP	13F 13D/G Company · STATE STREET CORPORATION 13F 13D/G	5% from 13D/G	$1,259,915,930 7,159,020 shares	—	31 Dec 2025
Caroline Dorsa	3/4/5 Director 3/4/5	0.02%	$3,931,673 31,002 shares	—	17 Jun 2025
VANGUARD GROUP INC	13F Company 13F	12%	$3,070,513,721 17,447,092 shares	—	31 Dec 2025

How to read this table

Rows are grouped by holder and ranked first by SEC-reported ownership % when it is safely comparable, then by disclosed holdings value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.

13F holder rows

Institutional holders as of Q1 2026

Investor-level positions for this CUSIP, loaded as an interactive table.

Institutions

1,003

134,906,238

Rows available

1,003

Investor	Option	Weight %	Change %	SEC-reported value	* Price	Shares	Share Change	Activity	Report Period

^* SEC-reported price is the security price as of the portfolio date and can indicate the last known price at which the security was still held. The marker flags a reported price that did not pass the local price check.

Compare Q1 2026 vs Q1 2026 Across Filers

Q1 2026 holders

1,003

Q1 2026 holders

1,003

Holder diff

Investor	Q1 2026 Shares	Q1 2026 Shares	Share Diff	Share Chg %	Q1 2026 value	Q1 2026 value	Value change	Value Chg %