Biogen Inc.
US ˙ NasdaqGS ˙ US09062X1037

SecurityBIIB / Biogen Inc.
InstitutionTocqueville Asset Management L.p.
Latest Disclosed Ownership4,352 shares
Latest Disclosed Value $ 797,852
Tocqueville Asset Management L.p. reports 20.42% decrease in ownership of BIIB / Biogen Inc.

On May 12, 2026 - Tocqueville Asset Management L.p. filed a 13F-HR form disclosing ownership of 4,352 shares of Biogen Inc. (US:BIIB) valued at $797,852 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 12, 2026 disclosing 5,469 shares of Biogen Inc.. This represents a change in shares of -20.42% during the quarter. The current value of the position is $850,120 USD.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

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Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date		 Effective
Date		Form Security Class ID Avg Price
Paid (Est)		 Reported
Shares		 ΔShares ΔShares
(%)		 Reported
Value
(x1000)		 ΔValue
(%)		 Alloc
(%)		 ΔAlloc ΔAlloc (%) Cost Basis
(x1000)		 Unrealized
Gain/Loss
(x1000)
2026-05-12 2026-03-31 13F BIOGEN COM 09062X103 4,352 -1,117 -20.42 798 -17.15 0.0118
2026-02-12 2025-12-31 13F BIOGEN COM 09062X103 5,469 -1,082 -16.52 962 4.91 0.0140
2025-11-13 2025-09-30 13F BIOGEN COM 09062X103 6,551 964 17.25 918 30.81 0.0133
2025-08-12 2025-06-30 13F BIOGEN COM 09062X103 5,587 -1,093 -16.36 702 -23.30 0.0107
2025-05-13 2025-03-31 13F BIOGEN COM 09062X103 6,680 -17,160 -71.98 914 -74.92 0.0149
2025-02-10 2024-12-31 13F BIOGEN COM 09062X103 23,840 -223,695 -90.37 3,646 -92.40 0.0572
2024-11-08 2024-09-30 13F BIOGEN COM 09062X103 247,535 27,537 12.52 47,982 -5.92 0.7537
2024-08-12 2024-06-30 13F BIOGEN COM 09062X103 219,998 173,798 376.19 51,000 411.94 0.8418
2024-05-09 2024-03-31 13F BIOGEN COM 09062X103 46,200 41,690 924.39 9,962 753.64 0.1627
2024-02-12 2023-12-31 13F BIOGEN COM 09062X103 4,510 289 6.85 1,167 7.66 0.0212
2023-11-09 2023-09-30 13F BIOGEN COM 09062X103 4,221 -8,029 -65.54 1,085 -68.93 0.0206
2023-08-11 2023-06-30 13F BIOGEN COM 09062X103 12,250 14 0.11 3,489 2.59 0.0625
2023-05-10 2023-03-31 13F BIOGEN COM 09062X103 12,236 176 1.46 3,402 1.86 0.0643
2023-02-09 2022-12-31 13F BIOGEN COM 09062X103 12,060 -1,761 -12.74 3,340 -9.51 0.0634
2022-11-10 2022-09-30 13F BIOGEN COM 09062X103 13,821 -1,378 -9.07 3,690 19.03 0.0752
2022-08-12 2022-06-30 13F BIOGEN COM 09062X103 15,199 -5,517 -26.63 3,100 -28.95 0.0567
2022-05-16 2022-03-31 13F Biogen COM 09062X103 20,716 -15,342 -42.55 4,363 -49.57 0.0659
2022-02-14 2021-12-31 13F BIOGEN COM 09062X103 36,058 -31,862 -46.91 8,651 -54.99 0.1190
2021-11-15 2021-09-30 13F BIOGEN COM 09062X103 67,920 -301 -0.44 19,221 -18.63 0.2847
2021-08-16 2021-06-30 13F BIOGEN COM 09062X103 68,221 -25,179 -26.96 23,623 -9.59 0.3413
2021-05-17 2021-03-31 13F BIOGEN COM 09062X103 93,400 4,007 4.48 26,129 19.37 0.4021
2021-02-16 2020-12-31 13F BIOGEN COM 09062X103 89,393 -24,020 -21.18 21,889 -31.96 0.3654
2020-11-16 2020-09-30 13F BIOGEN COM 09062X103 113,413 214 0.19 32,173 6.23 0.6155
2020-08-12 2020-06-30 13F BIOGEN COM 09062X103 113,199 -39,092 -25.67 30,286 -37.14 0.6316
2020-05-15 2020-03-31 13F BIOGEN COM 09062X103 152,291 16,474 12.13 48,182 19.56 1.1971
2020-01-14 2019-12-31 13F Biogen COM 09062X103 135,817 -3,769 -2.70 40,301 24.01 0.5927
2019-10-31 2019-09-30 13F Biogen COM 09062X103 139,586 -19,472 -12.24 32,498 -12.64 0.4410
2019-07-31 2019-06-30 13F Biogen COM 09062X103 159,058 -5,896 -3.57 37,199 -4.60 0.4821
2019-04-30 2019-03-31 13F Biogen COM 09062X103 164,954 5,990 3.77 38,992 -18.49 0.5205
2019-02-08 2018-12-31 13F Biogen COM 09062X103 158,964 -2,194 -1.36 47,835 -15.99 0.7168
2018-11-13 2018-09-30 13F Biogen COM 09062X103 161,158 1,920 1.21 56,939 23.20 0.7174
2018-08-13 2018-06-30 13F Biogen COM 09062X103 159,238 40,038 33.59 46,217 41.60 0.5863
2018-05-14 2018-03-31 13F Biogen COM 09062X103 119,200 3,153 2.72 32,639 -11.71 0.4158
2018-02-13 2017-12-31 13F Biogen COM 09062X103 116,047 3,321 2.95 36,969 4.74 0.4197
2017-10-30 2017-09-30 13F Biogen COM 09062X103 112,726 -2,742 -2.37 35,297 12.65 0.4060
2017-08-04 2017-06-30 13F Biogen COM 09062X103 115,468 7,317 6.77 31,333 5.96 0.3759
2017-04-28 2017-03-31 13F Biogen COM 09062X103 108,151 -8,123 -6.99 29,571 -10.32 0.3608
2017-01-30 2016-12-31 13F Biogen COM 09062X103 116,274 -70,274 -37.67 32,973 -43.53 0.4216
2016-10-31 2016-09-30 13F Biogen COM 09062X103 186,548 -1,080 -0.58 58,395 28.70 0.7011
2016-08-15 2016-06-30 13F/A-1 Biogen COM 09062X103 187,628 16,707 9.77 45,372 1.97 0.5406
2016-07-29 2016-06-30 13F Biogen COM 09062X103 187,628 45,372
2016-04-29 2016-03-31 13F Biogen COM 09062X103 170,921 9,821 6.10 44,494 -9.85 0.5893
2016-01-29 2015-12-31 13F Biogen COM 09062X103 161,100 3,959 2.52 49,353 7.63 0.6691
2015-10-30 2015-09-30 13F Biogen COM 09062X103 157,141 123,814 371.51 45,855 240.63 0.6134
2015-07-31 2015-06-30 13F Biogen COM 09062X103 33,327 2,175 6.98 13,462 2.34 0.1585
2015-04-30 2015-03-31 13F Biogen COM 09062X103 31,152 31,152 0.00 13,154 0.1546
2015-01-30 2014-12-31 13F Biogen Idec COM 09062X103 0 -27,561 -100.00 0 -100.00
2014-10-30 2014-09-30 13F Biogen Idec COM 09062X103 27,561 4,363 18.81 9,117 24.63 0.1012
2014-09-18 2014-06-30 13F/A-1 Biogen Idec COM 09062X103 23,198 155 0.67 7,315 3.79 0.0712
2014-07-30 2014-06-30 13F Biogen Idec COM 09062X103 23,198 7,315
2014-04-30 2014-03-31 13F Biogen Idec COM 09062X103 23,043 3,366 17.11 7,048 28.12 0.0928
2014-01-30 2013-12-31 13F Biogen Idec COM 09062X103 19,677 7,137 56.91 5,501 82.21 0.0739
2013-10-30 2013-09-30 13F Biogen Idec COM 09062X103 12,540 3,533 39.23 3,019 55.78 0.0376
2013-07-30 2013-06-30 13F Biogen Idec COM 09062X103 9,007 9,007 1,938 0.0262
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.