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BIIB in the 13F filings

Biogen Inc · CUSIP 09062X103

Sector · Pharmaceuticals and biotechnologyTheme · Biological productsTheme · Healthcare: biopharma and medtech· L3VLUP-defined
Quarter
Q3 2026 · early filersQ2 2026Q1 2026Q4 2025Q3 2025Q2 2025Q1 2025Q4 2024Q3 2024Q2 2024Q1 2024Q4 2023
Quarter end
31 Mar 2026
the date the book describes
Filed
27 Oct 2026
latest of these filings; the earliest 12 May 2026
Managers listing it
30
at least, of 95 tracked, among listed positions
Comparable managers
91
filed both Q4 2025 and Q1 2026; 18 listed it in both
Shares listed
24,577,083
combined, among listed positions
Reported value
$4.5bn
combined, at the quarter end

AllianceBernstein LP. Values in this filing are at the previous quarter end's prices; its share count is the quarter end's.

Among the 91 comparable managers: 13 buyers (opened or added shares) and 22 sellers (trimmed or exited), at least, among listed positions. Their net change in shares was -1,398,722.

Managers listing BIIB in Q1 2026

Share of 13F value is the position’s reported value over everything the manager reported that quarter. The share change is against Q4 2025, and only where both filings list the position. A rise in value with no rise in shares is the price, not buying.

30 of 30 holders

ActionFiling
Fidelity (FMR LLC)12,807,541$2.3bn0.12%Added+3,381,67815 May 2026 (the filing on sec.gov)
Wellington Management Group LLP2,961,641$543m0.10%Trimmed-589,62815 May 2026 (the filing on sec.gov)
AQR Capital Management LLC1,923,557$346m0.16%Added+394,94115 May 2026 (the filing on sec.gov)
Invesco Ltd1,745,255$320munder 0.1%Added+89,81412 May 2026 (the filing on sec.gov)
Point72 Asset Management LP809,617$148m0.19%Trimmed-2,003,57515 May 2026 (the filing on sec.gov)
MFS Investment Management720,629$134munder 0.1%Added+8,07014 May 2026 (the filing on sec.gov)
T. Rowe Price Associates Inc672,427$123munder 0.1%Trimmed-119,64415 May 2026 (the filing on sec.gov)
Balyasny Asset Management LLC650,046$119m0.15%Added+42,09315 May 2026 (the filing on sec.gov)
Man Group PLC318,745$58m0.11%Trimmed-20,53915 May 2026 (the filing on sec.gov)
Acadian Asset Management LLC248,489$46m0.06%Added+61,03213 May 2026 (the filing on sec.gov)
Marshall Wace LLP229,879$42munder 0.1%Trimmed-156,04915 May 2026 (the filing on sec.gov)
AllianceBernstein LP212,897$37munder 0.1%Added+29,15315 May 2026 (the filing on sec.gov)
Renaissance Technologies LLC203,396$37m0.06%Trimmed-195,80014 May 2026 (the filing on sec.gov)
Hudson Bay Capital Management LP201,367$37m0.13%Trimmed-20,49313 May 2026 (the filing on sec.gov)
ExodusPoint Capital Management LP151,993$28m0.22%Newnew14 May 2026 (the filing on sec.gov)
Susquehanna International Group LLP140,299$26munder 0.1%Trimmed-521,38515 May 2026 (the filing on sec.gov)
Citadel Advisors LLC138,093$25munder 0.1%Added+97,66915 May 2026 (the filing on sec.gov)
Woodline Partners LP109,032$20m0.08%Added+6,71415 May 2026 (the filing on sec.gov)
Millennium Management LLC93,964$17munder 0.1%Trimmed-1,031,62215 May 2026 (the filing on sec.gov)
Glenview Capital Management LLC57,019$10m0.26%Trimmed-233,58615 May 2026 (the filing on sec.gov)
Schonfeld Strategic Advisors LLC48,828$9.0m0.06%Trimmed-58,24015 May 2026 (the filing on sec.gov)
Squarepoint Ops LLC36,053$6.6munder 0.1%Trimmed-110,35515 May 2026 (the filing on sec.gov)
Walleye Capital LLC35,339$6.5munder 0.1%Added+33,76413 May 2026 (the filing on sec.gov)
Janus Henderson Group Ltd18,975$3.5munder 0.1%Trimmed-1,27718 May 2026 (the filing on sec.gov)
Neuberger Berman Group LLC11,651$2.1munder 0.1%Added+24727 Oct 2026 (the filing on sec.gov)
Page 1 of 2

Largest increases and reductions, by shares

Q4 2025 to Q1 2026, among managers that listed it in both quarters or opened it.

Increases

Reductions

New positions and exits

At least these many: a manager is shown exiting only where its own filing shows the position gone.

New (2)

Exited (6)

Ownership over time

Every quarter on file. A quarter-end value moves with the price as well as with the shares held; buyers and sellers count comparable managers, by shares.
17 in Q3 2024 to 12 in Q2 2026

Tracked managers listing it, at least.

0102030402014201620182020202220242026
the quarter shown share split complete books; unmarked quarters rest on listed positionsClick a quarter to open it.
BIIB by quarter
QuarterHoldersReported valueBuyersSellers
Q2 201323$12.7bnn.a.n.a.
Q3 201320$14.3bnn.a.n.a.
Q4 201320$16.1bnn.a.n.a.
Q1 201421$16.8bnn.a.n.a.
Q2 201418$16.8bnn.a.n.a.
Q3 201423$16.4bnn.a.n.a.
Q4 201422$15.7bnn.a.n.a.
Q1 201524$20.3bnn.a.n.a.
Q2 201524$20.5bnn.a.n.a.
Q3 201524$12.4bnn.a.n.a.
Q4 201527$11.9bnn.a.n.a.
Q1 201627$10.3bnn.a.n.a.
Q2 201624$9.5bnn.a.n.a.
Q3 201629$11.6bnn.a.n.a.
Q4 201631$10.9bnn.a.n.a.
Q1 201725$9.2bnn.a.n.a.
Q2 201728$9.8bnn.a.n.a.
Q3 201724$11.6bnn.a.n.a.
Q4 201722$11.8bnn.a.n.a.
Q1 201828$9.6bnn.a.n.a.
Q2 201825$8.9bnn.a.n.a.
Q3 201828$10.6bnn.a.n.a.
Q4 201828$9.0bnn.a.n.a.
Q1 201922$7.4bnn.a.n.a.
Q2 201928$7.2bnn.a.n.a.
Q3 201928$7.1bnn.a.n.a.
Q4 201927$7.7bnn.a.n.a.
Q1 202025$7.3bnn.a.n.a.
Q2 202029$5.1bnn.a.n.a.
Q3 202025$5.1bnn.a.n.a.
Q4 202022$4.6bnn.a.n.a.
Q1 202118$4.7bnn.a.n.a.
Q2 202125$5.4bnn.a.n.a.
Q3 202123$3.3bnn.a.n.a.
Q4 202125$3.7bnn.a.n.a.
Q1 202229$3.7bnn.a.n.a.
Q2 202225$3.4bnn.a.n.a.
Q3 202233$5.2bnn.a.n.a.
Q4 202228$5.0bnn.a.n.a.
Q1 202330$5.1bnn.a.n.a.
Q2 202323$4.4bnn.a.n.a.
Q3 202321$2.9bnn.a.n.a.
Q4 202317$2.8bn118
Q1 202416$2.5bn910
Q2 202414$2.5bn68
Q3 202417$2.6bn152
Q4 202420$2.6bn164
Q1 202522$2.4bn1510
Q2 202520$2.5bn155
Q3 202521$2.8bn138
Q4 202520$3.9bn1225
Q1 202616$3.9bn1322
Q2 202612$5.8bn1617

Compare with…

Holders over time, buyers and sellers, and the managers holding both, side by side for up to four stocks.

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How much of the picture this is

A 13F is a manager’s long US-listed equity book at a quarter end, filed up to 45 days later. It shows no shorts, cash, bonds or performance, and it is never today’s portfolio. Large books are listed to their largest positions, so a manager missing from this table may still hold a small position below that line. These are 95 tracked managers, not the institutional market.

Which funds own BIIB, latest filings →Back to the 13F Explorer →