BIOGEN INC (BIIB) Top Institutional Shareholders
BIOGEN INC (BIIB) is currently reported in institutional portfolios tracked by InsiderSet based on the latest available SEC Form 13F filings for the quarter ended March 31, 2026. The institutional investors covered on this page collectively reported approximately $23.75B in BIIB holdings during the latest filing period.
Blackrock, Inc. is currently the largest disclosed institutional shareholder of BIIB tracked by InsiderSet, reporting ownership valued at approximately $2.93B in its March 31, 2026 SEC Form 13F filing. Based on current market prices and the latest disclosed share count, the position is now estimated to be worth approximately $3.17B, representing an estimated gain of +8.37% since the filing period.
The top 10 institutional shareholders tracked on this page collectively account for approximately 61% of the total disclosed BIIB value among the investors covered in this analysis. Major shareholders include Blackrock, Inc., Primecap Management Co/Ca/, Fmr Llc, and several other long-term asset managers with concentrated positions in BIOGEN INC (BIIB).
This page ranks the largest institutional BIIB shareholders using publicly disclosed SEC Form 13F data, including reported values, estimated current holding values, portfolio allocation percentages, ownership concentration metrics, and historical holding changes across major hedge funds and investment firms.
Institutional Holders
987
Total Reported Value
$23.75B
Largest Holder
Blackrock, Inc.
Largest Position
$2.93B
Insider Transactions (90d)
0
Latest Filing Quarter
Q1 2026
New Institutional Positions
83
Funds Exiting Positions
0
| Name | Investor/Manager | Portfolio % | Quantity | Reported Balance | Current Estimated Value | Gain/loss Since Filing | Estimated Portfolio Performance |
|---|---|---|---|---|---|---|---|
| Blackrock, Inc. | 0.05% | 15,974,601 | $2,928,623,480 | $3,173,673,981 | +$245,050,501 | +8.37% | |
| Primecap Management Co/Ca/ | 2.13% | 14,757,607 | $2,705,512,094 | $2,931,893,783 | +$226,381,689 | +8.37% | |
| Fmr Llc | 0.12% | 12,807,541 | $2,348,006,582 | $2,544,474,170 | +$196,467,588 | +8.37% | |
| Vanguard Capital Management Llc | 0.04% | 9,537,417 | $1,748,494,659 | $1,894,798,635 | +$146,303,976 | +8.37% | |
| State Street Corp | 0.05% | 7,167,922 | $1,314,095,140 | $1,424,051,064 | +$109,955,924 | +8.37% | |
| Vanguard Portfolio Management Llc | 0.06% | 6,531,727 | $1,197,461,511 | $1,297,658,203 | +$100,196,692 | +8.37% | |
| Geode Capital Management, Llc | 0.05% | 4,342,602 | $793,387,370 | $862,744,739 | +$69,357,369 | +8.74% | |
| Wellington Management Group Llp | 0.10% | 2,961,641 | $542,957,645 | $588,389,217 | +$45,431,572 | +8.37% | |
| Storebrand Asset Management As | 0.15% | 1,678,578 | $455,795,304 | $333,483,091 | -$122,312,213 | -26.83% | |
| Morgan Stanley | 0.02% | 2,170,940 | $397,998,875 | $431,300,650 | +$33,301,775 | +8.37% | |
| Aqr Capital Management Llc | 0.16% | 1,923,557 | $346,240,270 | $382,153,069 | +$35,912,799 | +10.37% | |
| Invesco Ltd. | 0.05% | 1,745,255 | $319,957,584 | $346,729,811 | +$26,772,227 | +8.37% | |
| Boston Partners | 0.33% | 1,700,078 | $311,657,547 | $337,754,496 | +$26,096,949 | +8.37% | |
| Northern Trust Corp | 0.04% | 1,446,579 | $265,201,330 | $287,391,850 | +$22,190,520 | +8.37% | |
| Ubs Am, A Distinct Business Unit Of Ubs Asset Management Americas Llc | 0.05% | 1,377,568 | $252,549,543 | $273,681,435 | +$21,131,892 | +8.37% | |
| Legal & General Group Plc | 0.06% | 1,349,832 | $247,464,698 | $268,171,123 | +$20,706,425 | +8.37% | |
| Bank Of America Corp | 0.02% | 1,156,369 | $211,997,128 | $229,735,829 | +$17,738,701 | +8.37% | |
| Charles Schwab Investment Management Inc | 0.03% | 1,149,394 | $210,718,402 | $228,350,106 | +$17,631,704 | +8.37% | |
| Dimensional Fund Advisors Lp | 0.04% | 1,079,119 | $197,881,455 | $214,388,572 | +$16,507,117 | +8.34% | |
| Deutsche Bank Ag\ | 0.06% | 1,063,828 | $195,031,589 | $211,350,709 | +$16,319,120 | +8.37% | |
| Goldman Sachs Group Inc | 0.03% | 1,051,094 | $192,697,038 | $208,820,845 | +$16,123,807 | +8.37% | |
| Pictet Asset Management Holding Sa | 0.18% | 913,328 | $168,272,179 | $181,450,874 | +$13,178,695 | +7.83% | |
| Vanguard Fiduciary Trust Co | 0.04% | 825,531 | $151,344,598 | $164,008,244 | +$12,663,646 | +8.37% | |
| Point72 Asset Management, L.P. | 0.26% | 809,617 | $148,427,085 | $160,846,609 | +$12,419,524 | +8.37% | |
| Alyeska Investment Group, L.P. | 0.42% | 805,050 | $147,589,817 | $159,939,284 | +$12,349,467 | +8.37% | |
| Amundi | 0.04% | 790,827 | $144,982,314 | $157,113,600 | +$12,131,286 | +8.37% | |
| Bank Of New York Mellon Corp | 0.03% | 788,523 | $144,559,974 | $156,655,864 | +$12,095,890 | +8.37% | |
| Robeco Institutional Asset Management B.V. | 0.20% | 763,174 | $139,912,696 | $151,619,779 | +$11,707,083 | +8.37% | |
| Fred Alger Management, Llc | 0.59% | 733,194 | $134,416,456 | $145,663,652 | +$11,247,196 | +8.37% | |
| Massachusetts Financial Services Co | 0.04% | 720,629 | $133,702,279 | $143,167,363 | +$9,465,084 | +7.08% | |
| Employees Provident Fund Board | 0.98% | 704,196 | $129,100,253 | $139,902,619 | +$10,802,366 | +8.37% | |
| First Trust Advisors Lp | 0.09% | 673,958 | $123,556,618 | $133,895,236 | +$10,338,618 | +8.37% | |
| Balyasny Asset Management L.P. | 0.23% | 650,046 | $119,172,933 | $129,144,639 | +$9,971,706 | +8.37% | |
| Australiansuper Pty Ltd | 0.59% | 616,193 | $112,966,663 | $122,419,063 | +$9,452,400 | +8.37% | |
| Artemis Investment Management Llp | 1.11% | 571,571 | $104,786,111 | $113,554,011 | +$8,767,900 | +8.37% | |
| Barclays Plc | 0.04% | 551,474 | $101,101,725 | $109,561,340 | +$8,459,615 | +8.37% | |
| Royal Bank Of Canada | 0.02% | 531,377 | $97,418,000 | $105,568,669 | +$8,150,669 | +8.37% | |
| Ubs Group Ag | 0.02% | 523,450 | $95,964,089 | $103,993,812 | +$8,029,723 | +8.37% | |
| Zurcher Kantonalbank (Zurich Cantonalbank) | 0.21% | 522,155 | $95,726,676 | $103,736,534 | +$8,009,858 | +8.37% | |
| Caisse De Depot Et Placement Du Quebec | 0.15% | 518,694 | $95,092,171 | $103,048,937 | +$7,956,766 | +8.37% | |
| Citigroup Inc | 0.06% | 500,507 | $91,757,948 | $99,435,726 | +$7,677,778 | +8.37% | |
| Bnp Paribas Financial Markets | 0.06% | 471,068 | $86,360,896 | $93,587,080 | +$7,226,184 | +8.37% | |
| Hsbc Holdings Plc | 0.05% | 463,652 | $84,618,596 | $92,113,743 | +$7,495,147 | +8.86% | |
| Swiss National Bank | 0.05% | 430,600 | $78,941,898 | $85,547,302 | +$6,605,404 | +8.37% | |
| National Pension Service | 0.06% | 401,667 | $73,637,611 | $79,799,183 | +$6,161,572 | +8.37% | |
| Candriam S.C.A. | 0.36% | 381,768 | $69,989,527 | $75,845,849 | +$5,856,322 | +8.37% | |
| Patient Capital Management, Llc | 2.60% | 379,741 | $69,618,001 | $75,443,144 | +$5,825,143 | +8.37% | |
| Nuveen, Llc | 0.02% | 358,838 | $65,785,770 | $71,290,345 | +$5,504,575 | +8.37% | |
| Sumitomo Mitsui Trust Group, Inc. | 0.04% | 356,291 | $65,318,829 | $70,784,333 | +$5,465,504 | +8.37% | |
| Vanguard Global Advisers, Llc | 0.03% | 343,768 | $63,022,987 | $68,296,389 | +$5,273,402 | +8.37% |
Frequently asked questions about BIIB
Who owns the most BIIB stock?
The largest holders of BIIB are typically major institutional investors such as asset managers and hedge funds reporting on Form 13F. The table above ranks tracked superinvestors by reported position size using the latest available filings for BIOGEN INC (BIIB).
Is BIIB widely held by superinvestors?
Many widely followed stocks like BIIB appear across numerous superinvestor portfolios because of liquidity, index inclusion, and fundamentals. The holder count and table above show how broadly BIIB is represented among the institutional managers we track.
What do “Current Estimated Value”, “Gain/loss Since Filing”, and “Estimated Portfolio Performance” mean?
Current Estimated Value is reported share quantity from the latest 13F times our most recent split-adjusted U.S. session close. Gain/loss Since Filing is that estimate minus the reported 13F dollar value; Estimated Portfolio Performance is that difference as a percent of the reported value. Green means the estimate is above the filing value; red means below (not purchase cost). If many filers share the same implied filing price per share, the performance % may match across rows. These are not official fund marks or live quotes.