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BIIB · Biogen Inc. · Held by Funds

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$253.40 +2.92 (+1.17%) At close · Nov 13 Play latest call Q3 2026 earnings call transcript
S&P 500 member Russell 1000 member Rebalance outlook locked
Market Cap
$37.46B
Shares
147.82M
Volume · Nov 13 1.03M Avg daily vol (3M) 1.07M

Registered funds — mutual funds, ETFs and closed-end funds — whose latest Form N-PORT portfolio report holds this exact listed security, matched by CUSIP. Each row is one fund position with its size, value and weight in that fund.

Fund Ownership of BIIB by Fund Type

Registered funds' Form N-PORT reports for the quarter ended Jun 30, 2026

Index funds and index ETFs hold 22.91% of shares outstanding.

Fund type Of shares outstanding Shares
Index funds 4.86% 7,187,807
Index ETFs 18.04% 26,672,132
Active ETFs 0.49% 727,909
Active funds 23.96% 35,416,966
Unclassified 1.33% 1,964,325
All registered funds 48.69% 71,969,139
How fund types are measured

Each fund series counts once, with its latest Form N-PORT report dated inside the quarter; only long share positions count, restated to today's split basis. The fund type is the series' latest Form N-CEN answer on or before the quarter end (the index-fund box and the exchange-traded flag), never its name. Unclassified funds have no usable N-CEN; unit investment trusts are among them, so index ownership is a floor. Funds sit inside their advisers' 13F reports, so these shares overlap the 13F figures and are never added to them.

Funds holding BIIB

864 fund positions
Fund Balance Value % of Fund Open
VANGUARD PRIMECAP FUND 8,359,880 $1,806,235,673 1.88%
Fidelity Contrafund 4,988,655 $1,077,848,799 0.60%
VANGUARD TOTAL STOCK MARKET INDEX FUND 4,687,985 $1,012,886,039 0.04%
VANGUARD 500 INDEX FUND 3,827,862 $827,047,864 0.05%
VANGUARD MID-CAP INDEX FUND 3,199,078 $691,192,793 0.31%
VANGUARD CAPITAL OPPORTUNITY FUND 2,624,317 $567,009,931 1.73%
VANGUARD HEALTH CARE FUND 2,745,486 $557,196,384 1.46%
iShares Core S&P 500 ETF 2,031,041 $438,826,718 0.05%
Fidelity 500 Index Fund 1,916,462 $415,201,492 0.05%
State Street(R) SPDR(R) S&P 500(R) ETF Trust 1,791,761 $387,127,882 0.05%
Strategic Advisers Fidelity U.S. Total Stock Fund 1,629,734 $353,081,871 0.13%
VANGUARD VALUE INDEX FUND 1,403,950 $303,337,437 0.12%
VANGUARD PRIMECAP CORE FUND 1,316,936 $284,537,192 1.57%
Fidelity Contrafund K6 1,075,723 $232,420,711 0.62%
State Street(R) Health Care Select Sector SPDR(R) ETF 1,042,998 $225,350,148 0.56%
iShares Biotechnology ETF 1,037,164 $224,089,654 2.47%
VANGUARD MID-CAP VALUE INDEX FUND 948,250 $204,878,895 0.55%
Invesco S&P 500 Equal Weight ETF 960,126 $194,857,572 0.20%
VANGUARD INSTITUTIONAL INDEX FUND 801,523 $173,177,059 0.05%
Disciplined Value Mid Cap Fund 783,308 $169,241,526 0.73%
PRIMECAP Odyssey Aggressive Growth Fund 707,650 $143,617,568 1.94%
Pacer US Cash Cows 100 ETF 663,482 $134,653,672 0.72%
iShares Russell Mid-Cap ETF 606,371 $131,012,518 0.23%
Fidelity Low-Priced Stock Fund 627,560 $127,363,302 0.51%
Fidelity Series Value Discovery Fund 614,218 $124,655,543 0.70%
PRIMECAP Odyssey Growth Fund 612,000 $124,205,400 2.05%
Fidelity Mid Cap Index Fund 558,411 $113,329,512 0.22%
State Street(R) SPDR(R) S&P(R) Biotech ETF 512,556 $110,742,849 1.03%
PRIMECAP Odyssey Stock Fund 530,890 $107,744,126 2.34%
Select Biotechnology Portfolio 456,335 $98,864,978 1.57%
VANGUARD HEALTH CARE INDEX FUND 448,196 $97,101,663 0.44%
First Trust NYSE Arca Biotechnology Index Fund 438,784 $94,803,671 3.37%
MFS Mid Cap Value Fund 409,937 $88,570,988 0.51%
BlackRock Health Sciences Opportunities Portfolio 364,188 $78,901,330 1.24%
State Street(R) SPDR(R) Portfolio S&P 500(R) ETF 352,258 $76,108,863 0.05%
iShares Russell 1000 Value ETF 328,642 $71,006,391 0.09%
Pacer US Small Cap Cash Cows 100 ETF 345,939 $70,208,320 1.91%
Schwab S&P 500 Index Fund 329,910 $66,955,235 0.05%
Fidelity Total Market Index Fund 281,997 $61,094,650 0.04%
Fidelity Advisor Biotechnology Fund 294,100 $59,687,595 2.71%
PRIMECAP PORTFOLIO 263,550 $56,942,613 1.83%
Fidelity Puritan Fund 243,800 $52,819,270 0.16%
iShares S&P 500 Value ETF 242,515 $52,397,791 0.11%
Fidelity SAI U.S. Low Volatility Index Fund 246,972 $50,122,967 0.21%
Fidelity Series Total Market Index Fund 230,477 $49,932,842 0.04%
iShares Russell Mid-Cap Value ETF 225,930 $48,814,436 0.31%
Select Health Care Portfolio 200,000 $43,330,000 0.64%
T. Rowe Price Equity Income Fund 195,000 $42,131,700 0.24%
ALGER FOCUS EQUITY FUND 203,257 $41,251,008 0.58%
iShares Core S&P Total U.S. Stock Market ETF 189,910 $41,031,955 0.04%
Showing 1–50 of 864 positions
Key facts CIK 875045 CUSIP 09062X103 13F (30d) 852 filings 783 filers Visit website Investor relations