There is a long list of 914 institutional holders of Biogen within the last two holding periods in our database of 13F filers, so we've sorted through to present to you just the top 50 institutional holders of Biogen by largest to smallest position reported in the institutional investor's latest 13F filing. In the institutional-holders-of-Biogen table below, the initial column indicates the name of each top institutional holder of Biogen, with a link to that fund's top holdings. The next columns indicate the amount of Biogen stock held by each of the institutional holders of Biogen, followed by the Biogen position size held by the institution, and finally the date of the quarterly 13F filing period the holdings data represents for that institution.

Holder	Amount	Position Size ($ in 1000's)	As of
BlackRock Inc.	14,538,497	$3,370,314	06/30/2024
BIIB	14,538,497	$3,370,314	06/30/2024
Vanguard Group Inc.	16,678,507	$3,232,962	09/30/2024
BIIB	16,678,507	$3,232,962	09/30/2024
Primecap Management Co. CA	16,315,079	$3,162,515	09/30/2024
BIIB	16,315,079	$3,162,515	09/30/2024
BlackRock Inc.	15,347,041	$2,974,870	09/30/2024
BIIB	15,347,041	$2,974,870	09/30/2024
State Street Corp	7,344,960	$1,423,747	09/30/2024
BIIB	7,344,960	$1,423,747	09/30/2024
Wellington Management Group LLP	5,131,193	$994,630	09/30/2024
BIIB	5,131,193	$994,630	09/30/2024
JPMorgan Chase & Co.		$991,001	09/30/2024
BIIB	5,102,469	$989,063	09/30/2024
Call	19,000	$3,683	09/30/2024
Put	9,000	$1,745	09/30/2024
T. Rowe Price Investment Management Inc.	4,256,286	$825,039	09/30/2024
BIIB	4,256,286	$825,039	09/30/2024
Geode Capital Management LLC	3,613,020	$698,062	09/30/2024
BIIB	3,613,020	$698,062	09/30/2024
International Assets Investment Management LLC	358,992	$695,870	09/30/2024
BIIB	358,992	$695,870	09/30/2024
Price T Rowe Associates Inc. MD	1,912,546	$370,729	09/30/2024
BIIB	1,912,546	$370,729	09/30/2024
Morgan Stanley	1,887,246	$365,824	09/30/2024
BIIB	1,887,246	$365,824	09/30/2024
Beutel Goodman & Co Ltd.	1,744,154	$338,086	09/30/2024
BIIB	1,744,154	$338,086	09/30/2024
Invesco Ltd.	1,629,733	$315,907	09/30/2024
BIIB	1,629,733	$315,907	09/30/2024
Legal & General Group Plc	1,511,506	$292,990	09/30/2024
BIIB	1,511,506	$292,990	09/30/2024
Northern Trust Corp	1,353,135	$262,292	09/30/2024
BIIB	1,353,135	$262,292	09/30/2024
RA Capital Management L.P.	1,184,456	$229,595	09/30/2024
BIIB	1,184,456	$229,595	09/30/2024
UBS Asset Management Americas Inc.	1,152,691	$223,438	09/30/2024
BIIB	1,152,691	$223,438	09/30/2024
Ameriprise Financial Inc.	1,150,486	$223,012	09/30/2024
BIIB	1,150,486	$223,012	09/30/2024
Dimensional Fund Advisors LP	1,114,340	$216,010	09/30/2024
BIIB	1,114,340	$216,010	09/30/2024
Bank of New York Mellon Corp	1,003,135	$194,448	09/30/2024
BIIB	1,003,135	$194,448	09/30/2024
Goldman Sachs Group Inc.	989,041	$191,716	09/30/2024
BIIB	989,041	$191,716	09/30/2024
Renaissance Technologies LLC	952,706	$184,673	09/30/2024
BIIB	952,706	$184,673	09/30/2024
Barclays PLC		$177,006	09/30/2024
BIIB	921,256	$178,576	09/30/2024
Put	30,800	$5,970	09/30/2024
Call	22,700	$4,400	09/30/2024
Charles Schwab Investment Management Inc.	913,029	$176,982	09/30/2024
BIIB	913,029	$176,982	09/30/2024
Man Group plc	856,835	$166,089	09/30/2024
BIIB	856,835	$166,089	09/30/2024
Amundi	897,512	$163,616	09/30/2024
BIIB	897,512	$163,616	09/30/2024
Orbimed Advisors LLC	813,000	$157,592	09/30/2024
BIIB	813,000	$157,592	09/30/2024
Deutsche Bank AG	714,285	$138,457	09/30/2024
BIIB	714,285	$138,457	09/30/2024
Massachusetts Financial Services Co. MA	711,184	$137,856	09/30/2024
BIIB	711,184	$137,856	09/30/2024
Bank of America Corp DE		$127,246	09/30/2024
BIIB	658,151	$127,576	09/30/2024
Put	24,700	$4,788	09/30/2024
Call	23,000	$4,458	09/30/2024
Two Sigma Investments LP	648,702	$125,744	09/30/2024
BIIB	648,702	$125,744	09/30/2024
Clearbridge Investments LLC	601,986	$116,689	09/30/2024
BIIB	601,986	$116,689	09/30/2024
Standard Life Aberdeen plc	568,510	$110,123	09/30/2024
BIIB	568,510	$110,123	09/30/2024
Allianz Asset Management GmbH	525,513	$101,865	09/30/2024
BIIB	525,513	$101,865	09/30/2024
Pictet Asset Management Holding SA	472,525	$91,781	09/30/2024
BIIB	472,525	$91,781	09/30/2024
UBS Group AG		$90,456	09/30/2024
BIIB	503,853	$97,667	09/30/2024
Put	158,500	$30,724	09/30/2024
Call	121,300	$23,513	09/30/2024
Swiss National Bank	432,100	$83,758	09/30/2024
BIIB	432,100	$83,758	09/30/2024
Two Sigma Advisers LP	427,600	$82,886	09/30/2024
BIIB	427,600	$82,886	09/30/2024
Prudential Financial Inc.	423,284	$82,049	09/30/2024
BIIB	423,284	$82,049	09/30/2024
D. E. Shaw & Co. Inc.		$81,401	09/30/2024
BIIB	434,939	$84,309	09/30/2024
Put	17,400	$3,373	09/30/2024
Call	2,400	$465	09/30/2024
Hsbc Holdings PLC		$80,967	09/30/2024
BIIB	414,396	$80,269	09/30/2024
Call	4,500	$872	09/30/2024
Put	900	$174	09/30/2024
BNP Paribas Arbitrage SA		$78,362	09/30/2024
BIIB	413,360	$80,126	09/30/2024
Put	113	$2,190	09/30/2024
Call	22	$426	09/30/2024
BNP PARIBAS ASSET MANAGEMENT Holding S.A.	399,404	$77,420	09/30/2024
BIIB	399,404	$77,420	09/30/2024
California Public Employees Retirement System	395,071	$76,581	09/30/2024
BIIB	395,071	$76,581	09/30/2024
Millennium Management LLC		$74,093	09/30/2024
BIIB	398,136	$77,175	09/30/2024
Put	45,500	$8,820	09/30/2024
Call	29,600	$5,738	09/30/2024
FMR LLC	381,214	$73,895	09/30/2024
BIIB	381,214	$73,895	09/30/2024
TD Asset Management Inc.	371,001	$72,223	09/30/2024
BIIB	371,001	$72,223	09/30/2024
Franklin Resources Inc.	374,747	$71,787	09/30/2024
BIIB	374,747	$71,787	09/30/2024
Sumitomo Mitsui Trust Holdings Inc.	370,128	$71,746	09/30/2024
BIIB	370,128	$71,746	09/30/2024