Biogen Inc.
US ˙ NasdaqGS ˙ US09062X1037

SecurityBIIB / Biogen Inc.
InstitutionRitholtz Wealth Management
Latest Disclosed Ownership34,943 shares
Latest Disclosed Value $ 6,406,100
Ritholtz Wealth Management reports 23.15% increase in ownership of BIIB / Biogen Inc.

On April 20, 2026 - Ritholtz Wealth Management filed a 13F-HR form disclosing ownership of 34,943 shares of Biogen Inc. (US:BIIB) valued at $6,406,100 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 23, 2026 disclosing 28,375 shares of Biogen Inc.. This represents a change in shares of 23.15% during the quarter. The current value of the position is $6,825,766 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)
2026-04-20 2026-03-31 13F BIOGEN COM 09062X103 34,943 6,568 23.15 6,406 28.30 0.1111
2026-01-23 2025-12-31 13F BIOGEN COM 09062X103 28,375 16,695 142.94 4,994 205.20 0.0912
2025-10-28 2025-09-30 13F BIOGEN COM 09062X103 11,680 5,604 92.23 1,636 114.42 0.0318
2025-07-28 2025-06-30 13F BIOGEN COM 09062X103 6,076 6,076 763 0.0168
2023-04-19 2023-03-31 13F BIOGEN COM 09062X103 0 -725 -100.00 0 -100.00
2023-01-19 2022-12-31 13F BIOGEN COM 09062X103 725 -1,158 -61.50 201 -60.24 0.0112
2022-10-19 2022-09-30 13F BIOGEN COM 09062X103 1,883 345 22.43 503 60.19 0.0267
2022-07-15 2022-06-30 13F BIOGEN COM 09062X103 1,538 466 43.47 314 38.94 0.0198
2022-04-14 2022-03-31 13F BIOGEN COM 09062X103 1,072 -233 -17.85 226 -27.80 0.0153
2022-01-18 2021-12-31 13F BIOGEN COM 09062X103 1,305 -936 -41.77 313 -50.63 0.0195
2021-10-14 2021-09-30 13F BIOGEN COM 09062X103 2,241 2 0.09 634 -18.19 0.0440
2021-07-20 2021-06-30 13F BIOGEN COM 09062X103 2,239 702 45.67 775 80.23 0.0558
2021-05-12 2021-03-31 13F BIOGEN COM 09062X103 1,537 350 29.49 430 47.77 0.0358
2021-01-19 2020-12-31 13F BIOGEN COM 09062X103 1,187 -105 -8.13 291 -20.71 0.0279
2020-10-23 2020-09-30 13F BIOGEN COM 09062X103 1,292 525 68.45 367 79.02 0.0412
2020-07-15 2020-06-30 13F BIOGEN COM 09062X103 767 767 205 0.0264
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.