Biogen Inc.
US ˙ NasdaqGS ˙ US09062X1037

SecurityBIIB / Biogen Inc.
InstitutionShell Asset Management Co
Latest Disclosed Ownership5,448 shares
Latest Disclosed Value $ 763
Shell Asset Management Co reports 35.45% decrease in ownership of BIIB / Biogen Inc.

On November 7, 2025 - Shell Asset Management Co filed a 13F-HR form disclosing ownership of 5,448 shares of Biogen Inc. (US:BIIB) valued at $763,156 USD as of September 30, 2025. The entity filed a previous 13F-HR on July 23, 2025 disclosing 8,440 shares of Biogen Inc.. This represents a change in shares of -35.45% during the quarter. The current value of the position is $1,070,260 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)
2025-11-07 2025-09-30 13F BIOGEN COM 09062X103 5,448 -2,992 -35.45 1 -100.00 0.0766
2025-07-23 2025-06-30 13F BIOGEN COM 09062X103 8,440 4,488 113.56 1 0.0366
2025-05-14 2025-03-31 13F BIOGEN COM 09062X103 3,952 0 0.00 1 0.0257
2025-02-14 2024-12-31 13F BIOGEN COM 09062X103 3,952 -103 -2.54 1 0.0264
2024-11-07 2024-09-30 13F BIOGEN COM 09062X103 4,055 0 0.00 1 0.0346
2024-07-25 2024-03-31 13F BIOGEN COM 09062X103 4,055 -3,407 -45.66 1 -100.00 0.0428
2024-02-14 2023-12-31 13F BIOGEN COM 09062X103 7,462 2,430 48.29 2 0.00 0.0892
2023-11-08 2023-09-30 13F BIOGEN COM 09062X103 5,032 -143 -2.76 1 0.00 0.0534
2023-07-28 2023-06-30 13F BIOGEN COM 09062X103 5,175 -726 -12.30 1 0.00 0.0581
2023-05-15 2023-03-31 13F BIOGEN COM 09062X103 5,901 -24 -0.41 2 0.00 0.0681
2023-02-07 2022-12-31 13F BIOGEN COM 09062X103 5,925 -1,309 -18.10 2 -99.95 0.0719
2022-11-14 2022-09-30 13F BIOGEN COM 09062X103 7,234 -1,414 -16.35 1,931 9.47 0.0753
2022-08-09 2022-06-30 13F BIOGEN COM 09062X103 8,648 -52 -0.60 1,764 -3.71 0.0522
2022-05-04 2022-03-31 13F BIOGEN COM 09062X103 8,700 -338 -3.74 1,832 -15.50 0.0432
2022-02-09 2021-12-31 13F BIOGEN COM 09062X103 9,038 2,136 30.95 2,168 11.01 0.0445
2021-11-04 2021-09-30 13F BIOGEN COM 09062X103 6,902 -51 -0.73 1,953 -18.90 0.0438
2021-08-12 2021-06-30 13F BIOGEN COM 09062X103 6,953 -5,408 -43.75 2,408 -30.36 0.0467
2021-05-10 2021-03-31 13F BIOGEN COM 09062X103 12,361 -2,533 -17.01 3,458 -5.18 0.0692
2021-02-16 2020-12-31 13F BIOGEN COM 09062X103 14,894 2,504 20.21 3,647 3.76 0.0753
2020-11-13 2020-09-30 13F BIOGEN COM 09062X103 12,390 -33 -0.27 3,515 5.75 0.0817
2020-08-10 2020-06-30 13F BIOGEN COM 09062X103 12,423 3,075 32.89 3,324 12.37 0.0830
2020-05-11 2020-03-31 13F BIOGEN COM 09062X103 9,348 -2,162 -18.78 2,958 -13.38 0.0824
2020-02-13 2019-12-31 13F BIOGEN COM 09062X103 11,510 -94 -0.81 3,415 26.39 0.0736
2019-11-12 2019-09-30 13F BIOGEN COM 09062X103 11,604 0 0.00 2,702 -0.44 0.0617
2019-08-12 2019-06-30 13F BIOGEN COM 09062X103 11,604 -941 -7.50 2,714 -8.47 0.0601
2019-05-09 2019-03-31 13F BIOGEN COM 09062X103 12,545 -525 -4.02 2,965 -24.61 0.0654
2019-02-13 2018-12-31 13F BIOGEN COM 09062X103 13,070 -2,842 -17.86 3,933 -30.04 0.0980
2018-11-13 2018-09-30 13F BIOGEN COM 09062X103 15,912 42 0.26 5,622 22.06 0.1110
2018-08-10 2018-06-30 13F BIOGEN COM 09062X103 15,870 1,965 14.13 4,606 20.99 0.0944
2018-05-14 2018-03-31 13F BIOGEN COM 09062X103 13,905 -9,769 -41.26 3,807 -49.52 0.0758
2018-02-09 2017-12-31 13F BIOGEN COM 09062X103 23,674 3,319 16.31 7,542 18.32 0.1497
2017-10-20 2017-09-30 13F/A-1 BIOGEN COM 09062X103 20,355 -5,613 -21.62 6,374 -9.55 0.1417
2017-10-18 2017-09-30 13F BIOGEN COM 09062X103 38,882 12,914 12,863
2017-07-26 2017-06-30 13F BIOGEN COM 09062X103 25,968 -168 -0.64 7,047 -1.39 0.1749
2017-04-26 2017-03-31 13F BIOGEN COM 09062X103 26,136 -3,103 -10.61 7,146 -13.82 0.1824
2017-01-10 2016-12-31 13F BIOGEN COM 09062X103 29,239 -2,369 -7.49 8,292 -16.19 0.2242
2016-10-28 2016-09-30 13F BIOGEN COM 09062X103 31,608 -7,901 -20.00 9,894 3.56 0.2368
2016-07-25 2016-06-30 13F BIOGEN COM 09062X103 39,509 8,399 27.00 9,554 17.97 0.2216
2016-05-11 2016-03-31 13F BIOGEN COM 09062X103 31,110 3,684 13.43 8,099 -3.61 0.1939
2016-02-05 2015-12-31 13F BIOGEN COM 09062X103 27,426 -11,456 -29.46 8,402 -34.68 0.1984
2015-10-13 2015-09-30 13F BIOGEN COM 09062X103 38,882 6,743 20.98 12,863 -0.92 0.2038
2015-07-30 2015-06-30 13F BIOGEN COM 09062X103 32,139 -3,225 -9.12 12,982 -13.06 0.2598
2015-05-07 2015-03-31 13F BIOGEN COM 09062X103 35,364 35,364 0.00 14,932 0.2600
2015-02-04 2014-12-31 13F BIOGEN IDEC COM 09062X103 0 -38,882 -100.00 0 -100.00
2014-10-24 2014-09-30 13F BIOGEN IDEC COM 09062X103 38,882 -113 -0.29 12,863 4.61 0.1997
2014-08-08 2014-06-30 13F BIOGEN IDEC COM 09062X103 38,995 -4,820 -11.00 12,296 -8.25 0.1895
2014-05-07 2014-03-31 13F BIOGEN IDEC COM 09062X103 43,815 -114 -0.26 13,402 9.13 0.2227
2014-02-03 2013-12-31 13F/A-1 BIOGEN IDEC COM 09062X103 43,929 -21,365 -32.72 12,281 -21.88 0.2090
2014-01-27 2013-12-31 13F BIOGEN IDEC COM 09062X103 43,929 12,281
2013-10-28 2013-09-30 13F BIOGEN IDEC COM 09062X103 65,294 -1,635 -2.44 15,720 9.14 0.2888
2013-08-01 2013-06-30 13F BIOGEN IDEC COM 09062X103 66,929 66,929 14,403 0.2742
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.