Skip to main content
BIIB logo

BIIB · Biogen Inc. · Shareholders & Ownership

Track BIIB — free
$243.90 +10.42 (+4.46%)
Market Cap
$34.77B
Shares
147.64M
Volume · Oct 20 651.87K Avg daily vol (3M) 997.42K

Every disclosed holder of BIIB in one list: 13F institutions, Schedule 13D and 13G filers, insiders (Forms 3, 4 and 5) and registered funds, each from its own latest filing. Holders nest by CIK and SEC reporting links, never by name, and each is summed once.

Who Owns BIIB

13F quarter Sep 30, 2026, combined view: filers that have not filed yet carry their Jun 30, 2026 positions

No chart: the summed disclosures exceed shares outstanding, so they are not parts of one whole.

Holder group Shares % Out
Institutional (13F) 142,439,452 96.48%
Insiders (Forms 3, 4, 5) 321,429 0.22%
13D/G-only blocks 28,767,662 19.49%
Remaining 23,891,426 -16.18%
Registered funds (N-PORT, not summed) 72,879,416 49.36%

Shares outstanding: 147,637,117, the issuer's latest cover-page count restated onto today's split basis.

Remaining is negative: the summed disclosures exceed shares outstanding, as when filings are dated at different times or holders that do not disclose their links count the same shares. It is flagged, not clipped.

13D/G-only counts each filer's latest 13D or 13G that no 13F report of the listing contains, that names no 13F filer and that no counted insider files. Funds are never summed: their shares sit inside their advisers' 13F reports.

Holders of BIIB

# Holder Shares
1
FMR LLC
13F CIK 315066 · Holding company · Jun 30, 2026
carried, not yet filed for the newest quarter
18,217,239
1.1
FMR LLC
13G CIK 315066 · Holding company · Jun 30, 2026
Rule 13d-1(b), qualified institution, not summed
18,294,523
1.2
Fidelity Contrafund
Fund S000006037 · Registered fund · Jun 30, 2026
Fidelity Contrafund, not summed
4,988,655
1.3
Strategic Advisers Fidelity U.S. Total Stock Fund
Fund S000061481 · Registered fund · May 31, 2026
Fidelity Rutland Square Trust II, not summed
2,027,406
1.4
Fidelity 500 Index Fund
Fund S000006027 · Registered fund · May 31, 2026
Fidelity Concord Street Trust, not summed
1,878,080
1.5
Fidelity Contrafund K6
Fund S000057289 · Registered fund · Jun 30, 2026
Fidelity Contrafund, not summed
1,075,723
2
BlackRock, Inc.
13F CIK 2012383 · Holding company · Jun 30, 2026
carried, not yet filed for the newest quarter
15,985,736
2.1
iShares Core S&P 500 ETF
Fund S000004310 · Registered fund · Jun 30, 2026
iShares Trust, not summed
2,031,041
2.2
iShares Biotechnology ETF
Fund S000004350 · Registered fund · Jun 30, 2026
iShares Trust, not summed
1,037,164
2.3
iShares Russell Mid-Cap ETF
Fund S000004338 · Registered fund · Jun 30, 2026
iShares Trust, not summed
606,371
2.4
BlackRock Health Sciences Opportunities Portfolio
Fund S000001877 · Registered fund · May 29, 2026
BlackRock Funds, not summed
364,188
2.5
iShares Russell 1000 Value ETF
Fund S000004345 · Registered fund · Jun 30, 2026
iShares Trust, not summed
328,642
3
PRIMECAP MANAGEMENT CO/CA/
13F CIK 763212 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
15,154,606
3.1
VANGUARD PRIMECAP FUND
Fund S000002568 · Registered fund · Jun 30, 2026
VANGUARD CHESTER FUNDS, not summed
8,359,880
3.2
VANGUARD CAPITAL OPPORTUNITY FUND
Fund S000002594 · Registered fund · Jun 30, 2026
VANGUARD HORIZON FUNDS, not summed
2,624,317
3.3
VANGUARD PRIMECAP CORE FUND
Fund S000002581 · Registered fund · Jun 30, 2026
VANGUARD FENWAY FUNDS, not summed
1,316,936
3.4
PRIMECAP Odyssey Aggressive Growth Fund
Fund S000005541 · Registered fund · Jul 31, 2026
PRIMECAP Odyssey Funds, not summed
707,650
3.5
PRIMECAP Odyssey Growth Fund
Fund S000005540 · Registered fund · Jul 31, 2026
PRIMECAP Odyssey Funds, not summed
612,000
4
VANGUARD GROUP INC
13G CIK 102909 · Registered investment adviser · Jan 31, 2024
Rule 13d-1(b), qualified institution
14,521,342
5
BlackRock Inc.
13G CIK 1364742 · Unknown · Dec 31, 2023
Rule 13d-1(b), qualified institution
14,246,320
6
VANGUARD CAPITAL MANAGEMENT LLC
13F CIK 2100119 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
9,651,117
7
STATE STREET CORP
13F CIK 93751 · Bank · Jun 30, 2026
carried, not yet filed for the newest quarter
7,344,327
7.1
State Street(R) Health Care Select Sector SPDR(R) ETF
Fund S000006412 · Registered fund · Jun 30, 2026
SELECT SECTOR SPDR TRUST, not summed
1,042,998
7.2
State Street(R) SPDR(R) S&P(R) Biotech ETF
Fund S000010018 · Registered fund · Jun 30, 2026
SPDR SERIES TRUST, not summed
512,556
7.3
State Street(R) SPDR(R) Portfolio S&P 500(R) ETF
Fund S000006983 · Registered fund · Jun 30, 2026
SPDR SERIES TRUST, not summed
352,258
7.4
State Street(R) SPDR(R) Portfolio S&P 500(R) Value ETF
Fund S000006985 · Registered fund · Jun 30, 2026
SPDR SERIES TRUST, not summed
178,821
7.5
State Street Equity 500 Index II Portfolio
Fund S000046029 · Registered fund · Jun 30, 2026
STATE STREET INSTITUTIONAL INVESTMENT TRUST, not summed
55,084
8
VANGUARD PORTFOLIO MANAGEMENT LLC
13F CIK 2100121 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
6,604,936
9
VANGUARD TOTAL STOCK MARKET INDEX FUND
Fund S000002848 · Registered fund · Jun 30, 2026
VANGUARD INDEX FUNDS, not summed
4,687,985
10
GEODE CAPITAL MANAGEMENT, LLC
13F CIK 1214717 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
4,449,295
11
VANGUARD 500 INDEX FUND
Fund S000002839 · Registered fund · Jun 30, 2026
VANGUARD INDEX FUNDS, not summed
3,827,862
12
VANGUARD MID-CAP INDEX FUND
Fund S000002844 · Registered fund · Jun 30, 2026
VANGUARD INDEX FUNDS, not summed
3,199,078
13
WELLINGTON MANAGEMENT GROUP LLP
13F CIK 902219 · Holding company · Jun 30, 2026
carried, not yet filed for the newest quarter
3,117,469
13.1
VANGUARD HEALTH CARE FUND
Fund S000002922 · Registered fund · Jul 31, 2026
VANGUARD SPECIALIZED FUNDS, not summed
2,745,486
14
NORGES BANK
13F CIK 1374170 · Non-US institution · Jun 30, 2026
carried, not yet filed for the newest quarter
2,580,033
15
MORGAN STANLEY
13F CIK 895421 · Holding company · Jun 30, 2026
carried, not yet filed for the newest quarter
2,411,271
15.1
Advantage Portfolio
Fund S000027993 · Registered fund · Jun 30, 2026
MORGAN STANLEY INSTITUTIONAL FUND INC, not summed
8,748
15.2
Global Strategist Portfolio
Fund S000004124 · Registered fund · Jun 30, 2026
MORGAN STANLEY INSTITUTIONAL FUND TRUST, not summed
490
15.3
E*TRADE No Fee Large Cap Index Fund
Fund S000090720 · Registered fund · Jul 31, 2026
E Trade Trust, not summed
317
15.4
E*TRADE No Fee Total Market Index Fund
Fund S000090722 · Registered fund · Jul 31, 2026
E Trade Trust, not summed
231
15.5
Global Strategist Portfolio
Fund S000004181 · Registered fund · Jun 30, 2026
MORGAN STANLEY VARIABLE INSURANCE FUND INC., not summed
64
16
AQR CAPITAL MANAGEMENT LLC
13F CIK 1167557 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
1,936,859
16.1
AQR Style Premia Alternative Fund
Fund S000042050 · Registered fund · Jun 30, 2026
AQR Funds, not summed
74,303
16.2
AQR Long-Short Equity Fund
Fund S000041116 · Registered fund · Jun 30, 2026
AQR Funds, not summed
48,898
16.3
AQR Equity Market Neutral Fund
Fund S000046740 · Registered fund · Jun 30, 2026
AQR Funds, not summed
22,140
16.4
AQR Alternative Risk Premia Fund
Fund S000058563 · Registered fund · Jun 30, 2026
AQR Funds, not summed
11,413
16.5
AQR Large Cap Multi-Style Fund
Fund S000040063 · Registered fund · Jun 30, 2026
AQR Funds, not summed
10,843
17
JPMORGAN CHASE & CO
13F CIK 19617 · Bank · Jun 30, 2026
carried, not yet filed for the newest quarter
1,823,140
18
Invesco Ltd.
13F CIK 914208 · Investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
1,803,944
18.1
Invesco S&P 500 Equal Weight ETF
Fund S000060812 · Registered fund · Jul 31, 2026
Invesco Exchange-Traded Fund Trust, not summed
960,126
18.2
Invesco NASDAQ Next Gen 100 ETF
Fund S000069449 · Registered fund · May 31, 2026
Invesco Exchange-Traded Fund Trust II, not summed
75,778
18.3
Invesco Equally-Weighted S&P 500 Fund
Fund S000027817 · Registered fund · May 31, 2026
AIM Counselor Series Trust (Invesco Counselor Series Trust), not summed
70,583
18.4
Invesco Biotechnology & Genome ETF
Fund S000003026 · Registered fund · Jul 31, 2026
Invesco Exchange-Traded Fund Trust, not summed
66,507
18.5
Invesco Pharmaceuticals ETF
Fund S000003031 · Registered fund · Jul 31, 2026
Invesco Exchange-Traded Fund Trust, not summed
63,929
19
Amundi
13F CIK 1330387 · Holding company · Jun 30, 2026
carried, not yet filed for the newest quarter
1,516,831
20
Legal & General Group Plc
13F CIK 764068 · Unknown · Jun 30, 2026
carried, not yet filed for the newest quarter
1,493,289
21
NORTHERN TRUST CORP
13F CIK 73124 · Bank · Jun 30, 2026
carried, not yet filed for the newest quarter
1,429,490
21.1
Stock Index Fund
Fund S000001247 · Registered fund · Jun 30, 2026
Northern Funds, not summed
45,274
21.2
World Selection Index Fund
Fund S000019579 · Registered fund · Jun 30, 2026
Northern Funds, not summed
6,826
21.3
FlexShares Morningstar US Market Factor Tilt Index Fund
Fund S000033312 · Registered fund · Jul 31, 2026
FlexShares Trust, not summed
4,108
22
VANGUARD VALUE INDEX FUND
Fund S000002840 · Registered fund · Jun 30, 2026
VANGUARD INDEX FUNDS, not summed
1,403,950
23
Boston Partners
13F CIK 1386060 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
1,263,429
24
UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC
13F CIK 861177 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
1,255,168
24.1
UBS U.S. Allocation Fund
Fund S000002487 · Registered fund · May 31, 2026
UBS INVESTMENT TRUST, not summed
87
24.2
UBS GLOBAL ALLOCATION FUND
Fund S000002979 · Registered fund · Jun 30, 2026
UBS FUNDS, not summed
40
25
GOLDMAN SACHS GROUP INC
13F CIK 886982 · Unknown · Jun 30, 2026
carried, not yet filed for the newest quarter
1,230,390
25.1
Goldman Sachs ActiveBeta(R) U.S. Large Cap Equity ETF
Fund S000048295 · Registered fund · May 31, 2026
Goldman Sachs ETF Trust, not summed
183,560
25.2
Goldman Sachs Equal Weight U.S. Large Cap Equity ETF
Fund S000058070 · Registered fund · May 31, 2026
Goldman Sachs ETF Trust, not summed
18,178
25.3
Goldman Sachs S&P 500 Premium Income ETF
Fund S000081511 · Registered fund · Jun 30, 2026
Goldman Sachs ETF Trust, not summed
9,883
25.4
Goldman Sachs MarketBeta U.S. Equity ETF
Fund S000066535 · Registered fund · May 31, 2026
Goldman Sachs ETF Trust, not summed
7,255
25.5
Goldman Sachs Absolute Return Tracker Fund
Fund S000020314 · Registered fund · Jun 30, 2026
GOLDMAN SACHS TRUST, not summed
6,282
26
DIMENSIONAL FUND ADVISORS LP
13F CIK 354204 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
1,148,568
26.1
THE U.S. LARGE CAP VALUE SERIES
Fund S000000993 · Registered fund · Jul 31, 2026
DFA INVESTMENT TRUST CO, not summed
142,489
26.2
Dimensional U.S. Core Equity 2 ETF
Fund S000070903 · Registered fund · Jul 31, 2026
Dimensional ETF Trust, not summed
114,920
26.3
Dimensional U.S. Marketwide Value ETF
Fund S000075030 · Registered fund · Jul 31, 2026
Dimensional ETF Trust, not summed
66,897
26.4
U.S. CORE EQUITY 1 PORTFOLIO
Fund S000000979 · Registered fund · Jul 31, 2026
DFA INVESTMENT DIMENSIONS GROUP INC, not summed
58,048
26.5
U.S. CORE EQUITY 2 PORTFOLIO
Fund S000000980 · Registered fund · Jul 31, 2026
DFA INVESTMENT DIMENSIONS GROUP INC, not summed
55,657
27
Pacer Advisors, Inc.
13F CIK 1616667 · Unknown · Jun 30, 2026
carried, not yet filed for the newest quarter
1,122,981
28
CHARLES SCHWAB INVESTMENT MANAGEMENT INC
13F CIK 884546 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
1,117,663
28.1
Schwab S&P 500 Index Fund
Fund S000005911 · Registered fund · Jul 31, 2026
SCHWAB CAPITAL TRUST, not summed
329,910
28.2
Schwab Fundamental U.S. Large Company ETF
Fund S000040877 · Registered fund · May 31, 2026
SCHWAB STRATEGIC TRUST, not summed
159,823
28.3
Schwab U.S. Large-Cap ETF
Fund S000026632 · Registered fund · May 31, 2026
SCHWAB STRATEGIC TRUST, not summed
156,596
28.4
Schwab Total Stock Market Index Fund
Fund S000005913 · Registered fund · Jul 31, 2026
SCHWAB CAPITAL TRUST, not summed
89,538
28.5
Schwab U.S. Broad Market ETF
Fund S000026631 · Registered fund · May 31, 2026
SCHWAB STRATEGIC TRUST, not summed
87,253
29
BANK OF AMERICA CORP /DE/
13F CIK 70858 · Bank · Jun 30, 2026
carried, not yet filed for the newest quarter
1,116,228
30
UBS Group AG
13F CIK 1610520 · Bank · Jun 30, 2026
carried, not yet filed for the newest quarter
1,030,150
31
VANGUARD MID-CAP VALUE INDEX FUND
Fund S000012757 · Registered fund · Jun 30, 2026
VANGUARD INDEX FUNDS, not summed
948,250
32
Alyeska Investment Group, L.P.
13F CIK 1453072 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
932,374
33
DEUTSCHE BANK AG\
13F CIK 948046 · Non-US institution · Jun 30, 2026
carried, not yet filed for the newest quarter
894,035
33.1
DWS Health and Wellness Fund
Fund S000006103 · Registered fund · May 31, 2026
DEUTSCHE DWS SECURITIES TRUST, not summed
11,150
33.2
Xtrackers S&P 500 Scored & Screened ETF
Fund S000065220 · Registered fund · May 29, 2026
DBX ETF Trust, not summed
10,064
33.3
Xtrackers MSCI USA Climate Action Equity ETF
Fund S000079909 · Registered fund · May 29, 2026
DBX ETF Trust, not summed
8,846
33.4
DWS Enhanced Core Equity Fund
Fund S000062621 · Registered fund · May 31, 2026
DEUTSCHE DWS INVESTMENT TRUST, not summed
6,023
33.5
Deutsche DWS Equity 500 Index Portfolio
Fund S000009010 · Registered fund · Jun 30, 2026
DEUTSCHE DWS EQUITY 500 INDEX PORTFOLIO, not summed
4,549
34
Pictet Asset Management Holding SA
13F CIK 1993888 · Unknown · Jun 30, 2026
carried, not yet filed for the newest quarter
851,819
35
VANGUARD FIDUCIARY TRUST CO
13F CIK 933478 · Unknown · Jun 30, 2026
carried, not yet filed for the newest quarter
829,318
36
VANGUARD INSTITUTIONAL INDEX FUND
Fund S000002853 · Registered fund · Jun 30, 2026
VANGUARD INSTITUTIONAL INDEX FUNDS, not summed
801,523
37
Robeco Institutional Asset Management B.V.
13F CIK 1418773 · Unknown · Jun 30, 2026
carried, not yet filed for the newest quarter
791,092
38
FRED ALGER MANAGEMENT, LLC
13F CIK 3520 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
788,307
38.1
ALGER FOCUS EQUITY FUND
Fund S000009201 · Registered fund · Jul 31, 2026
ALGER INSTITUTIONAL FUNDS, not summed
203,257
38.2
ALGER SPECTRA FUND
Fund S000009190 · Registered fund · Jul 31, 2026
ALGER FUNDS II, not summed
105,355
38.3
ALGER CAPITAL APPRECIATION INSTITUTIONAL FUND
Fund S000009204 · Registered fund · Jul 31, 2026
ALGER INSTITUTIONAL FUNDS, not summed
90,930
38.4
ALGER CAPITAL APPRECIATION FUND
Fund S000009163 · Registered fund · Jul 31, 2026
ALGER FUNDS, not summed
72,954
38.5
ALGER MID CAP FOCUS FUND
Fund S000063650 · Registered fund · Jul 31, 2026
ALGER FUNDS, not summed
34,390
39
PRICE T ROWE ASSOCIATES INC /MD/
13F CIK 80255 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
774,283
39.1
T. Rowe Price Equity Income Fund
Fund S000002076 · Registered fund · Jun 30, 2026
T. ROWE PRICE EQUITY INCOME FUND, INC., not summed
195,000
39.2
T. Rowe Price Capital Appreciation Equity ETF
Fund S000079834 · Registered fund · Jun 30, 2026
T. Rowe Price Exchange-Traded Funds, Inc., not summed
98,454
39.3
T. Rowe Price Equity Index 500 Fund
Fund S000002089 · Registered fund · Jun 30, 2026
T. ROWE PRICE INDEX TRUST, INC., not summed
90,520
39.4
T. Rowe Price U.S. Equity Research Fund
Fund S000002071 · Registered fund · Jun 30, 2026
T. Rowe Price U.S. Equity Research Fund, Inc., not summed
28,061
39.5
T. Rowe Price Equity Income Portfolio
Fund S000002077 · Registered fund · Jun 30, 2026
T. ROWE PRICE EQUITY SERIES, INC., not summed
10,535
40
Bank of New York Mellon Corp
13F CIK 1390777 · Bank · Jun 30, 2026
carried, not yet filed for the newest quarter
773,619
40.1
BNY Mellon US Large Cap Core Equity ETF
Fund S000067260 · Registered fund · Jul 31, 2026
BNY Mellon ETF Trust, not summed
12,295
41
MASSACHUSETTS FINANCIAL SERVICES CO /MA/
13F CIK 912938 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
744,892
41.1
MFS Mid Cap Value Fund
Fund S000002499 · Registered fund · Jun 30, 2026
MFS SERIES TRUST XI, not summed
409,937
41.2
MFS Blended Research Mid Cap Equity Fund
Fund S000054892 · Registered fund · May 31, 2026
MFS Series Trust X, not summed
113,786
41.3
MFS Mid Cap Value Portfolio
Fund S000018843 · Registered fund · Jun 30, 2026
MFS VARIABLE INSURANCE TRUST III, not summed
15,402
41.4
MFS Global Alternative Strategy Fund
Fund S000019515 · Registered fund · Jul 31, 2026
MFS Series Trust XV, not summed
194
41.5
MFS Blended Research Core Equity ETF
Fund S000095645 · Registered fund · May 31, 2026
MFS Active Exchange Traded Funds Trust, not summed
165
42
CITIGROUP INC
13F CIK 831001 · Bank · Jun 30, 2026
carried, not yet filed for the newest quarter
734,517
43
ROYAL BANK OF CANADA
13F CIK 1000275 · Bank · Jun 30, 2026
carried, not yet filed for the newest quarter
708,562
44
Employees Provident Fund Board
13F CIK 1600177 · Unknown · Jun 30, 2026
carried, not yet filed for the newest quarter
704,196
45
FIRST TRUST ADVISORS LP
13F CIK 1125816 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
682,021
45.1
First Trust NYSE Arca Biotechnology Index Fund
Fund S000012478 · Registered fund · Jun 30, 2026
First Trust Exchange-Traded Fund, not summed
438,784
45.2
First Trust Health Care AlphaDEX Fund
Fund S000017700 · Registered fund · Jul 31, 2026
First Trust Exchange-Traded AlphaDEX Fund, not summed
65,899
45.3
First Trust Large Cap Value AlphaDEX Fund
Fund S000017340 · Registered fund · Jul 31, 2026
First Trust Exchange-Traded AlphaDEX Fund, not summed
32,506
45.4
First Trust Long/Short Equity ETF
Fund S000045700 · Registered fund · Jul 31, 2026
First Trust Exchange-Traded Fund III, not summed
29,224
45.5
First Trust Large Cap Core AlphaDEX Fund
Fund S000017337 · Registered fund · Jul 31, 2026
First Trust Exchange-Traded AlphaDEX Fund, not summed
19,565
46
AustralianSuper Pty Ltd
13F CIK 1694164 · Non-US institution · Jun 30, 2026
carried, not yet filed for the newest quarter
672,723
47
Pacer US Cash Cows 100 ETF
Fund S000055466 · Registered fund · Jul 31, 2026
Pacer Funds Trust, not summed
663,482
48
Artemis Investment Management LLP
13F CIK 1535385 · Non-US institution · Sep 30, 2026
581,774
49
Zurcher Kantonalbank (Zurich Cantonalbank)
13F CIK 1368163 · Unknown · Jun 30, 2026
carried, not yet filed for the newest quarter
540,001
50
HSBC HOLDINGS PLC
13F CIK 873630 · Unknown · Jun 30, 2026
carried, not yet filed for the newest quarter
527,866

223 more nested rows are not shown here; Every filing lists them all.

Shares are restated onto today's split basis. Change compares each row with the same holder's previous filing in the same source; a dash means there is none to compare. Nested 13D/G, insider and fund rows are not summed, since a 13F report already holds them.

Showing 1–50 of 1,360 holders

Create a free account to page through every holder, filter by source and group by ultimate parent.

Key facts CIK 875045 CUSIP 09062X103 13F (30d) 163 filings 148 filers Visit website Investor relations