Biogen Inc.
US ˙ NasdaqGS ˙ US09062X1037

SecurityBIIB / Biogen Inc.
InstitutionAdvisor Group Holdings, Inc.
Latest Disclosed Ownership12,005 shares
Latest Disclosed Value $ 2,200,712
Advisor Group Holdings, Inc. ownership in BIIB / Biogen Inc.

On May 15, 2026 - Advisor Group Holdings, Inc. filed a 13F-HR form disclosing ownership of 12,005 shares of Biogen Inc. (US:BIIB) valued at $2,200,877 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 14,447 shares of Biogen Inc.. This represents a change in shares of -16.90% during the quarter. The current value of the position is $2,345,057 USD.

Advisor Group Holdings, Inc. has a history of taking positions in derivatives of the underlying security (BIIB) in the form of stock options.

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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Institutional Put/Call Ratios
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In addition to reporting standard equity and debt issues, institutions with more than 100MM assets under management must also disclose their put and call option holdings. Since put options generally indicate negative sentiment, and call options indicate positive sentiment, we can get a sense of the overall institutional sentiment by plotting the ratio of puts to calls. The chart to the right plots the historical put/call ratio for this instrument.

Using Put/Call Ratio as an indicator of investor sentiment overcomes one of the key deficiencies of using total institutional ownership, which is that a significant amount of assets under management are invested passively to track indices. Passively-managed funds do not typically buy options, so the put/call ratio indicator more closely tracks the sentiment of actively-managed funds.

BIIB / Biogen Inc. Historical Put/Call Ratio
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)
2026-05-15 2026-03-31 13F BIOGEN COM 09062X103 12,005 -2,442 -16.90 2,201 -13.45 0.0019
2026-02-17 2025-12-31 13F BIOGEN COM 09062X103 14,447 2,854 24.62 2,543 60.99 0.0037
2025-11-14 2025-09-30 13F BIOGEN COM 09062X103 11,593 2,858 32.72 1,579 43.94 0.0022
2025-09-04 2025-06-30 13F/A-1 IOGEN COM 09062X103 8,735 941 12.07 1,098 2.91 0.0020
2025-08-13 2025-06-30 13F IOGEN COM 09062X103 9,360 1,566 1,390 0.0016
2025-05-12 2025-03-31 13F BIOGEN COM 09062X103 7,794 -1,160 -12.96 1,066 -22.08 0.0024
2025-06-06 2024-12-31 13F/A-1 BIOGEN COM 09062X103 8,954 -2,176 -19.55 1,369 -36.58 0.0031
2025-02-07 2024-12-31 13F BIOGEN COM 09062X103 9,987 -1,143 1,889 0.0048
2024-11-13 2024-09-30 13F BIOGEN COM 09062X103 11,130 -2,435 -17.95 2,157 -31.39 0.0049
2024-08-13 2024-06-30 13F BIOGEN COM 09062X103 13,565 -2,742 -16.81 3,145 -10.58 0.0074
2024-05-10 2024-03-31 13F BIOGEN COM 09062X103 16,307 -2,426 -12.95 3,516 -27.45 0.0079
2024-02-12 2023-12-31 13F BIOGEN COM 09062X103 18,733 -16,020 -46.10 4,846 -45.74 0.0085
2023-11-13 2023-09-30 13F BIOGEN COM 09062X103 34,753 9,765 39.08 8,932 25.63 0.0132
2023-08-21 2023-06-30 13F/A-1 BIOGEN COM 09062X103 24,988 -881 -3.41 7,110 -1.32 0.0128
2023-08-10 2023-06-30 13F BIOGEN COM 09062X103 34,072 8,203 7,100 0.0019
2023-05-12 2023-03-31 13F BIOGEN COM 09062X103 25,869 -4,775 -15.58 7,204 -15.11 0.0136
2023-02-10 2022-12-31 13F BIOGEN COM 09062X103 30,644 5,677 22.74 8,486 27.28 0.0172
2022-11-14 2022-09-30 13F BIOGEN COM 09062X103 24,967 2,082 9.10 6,667 42.40 0.0152
2022-08-10 2022-06-30 13F BIOGEN COM 09062X103 22,885 679 3.06 4,682 -2.68 0.0103
2022-05-04 2022-03-31 13F BIOGEN COM 09062X103 22,206 1,421 6.84 4,811 -3.70 0.0093
2022-02-03 2021-12-31 13F BIOGEN COM 09062X103 20,785 -12,688 -37.91 4,996 -47.27 0.0095
2021-11-05 2021-09-30 13F BIOGEN COM 09062X103 33,473 -2,967 -8.14 9,474 -24.97 0.0197
2021-08-02 2021-06-30 13F BIOGEN COM 09062X103 36,440 -2,651 -6.78 12,627 15.48 0.0273
2021-05-13 2021-03-31 13F BIOGEN COM 09062X103 39,091 3,775 10.69 10,934 26.45 0.0263
2021-02-10 2020-12-31 13F BIOGEN COM 09062X103 35,316 1,139 3.33 8,647 -10.44 0.0231
2020-11-12 2020-09-30 13F BIOGEN COM 09062X103 34,177 5,194 17.92 9,655 24.47 0.0289
2020-08-14 2020-06-30 13F BIOGEN COM 09062X103 28,983 -47,367 -62.04 7,757 -22.58 0.0260
2020-05-18 2020-03-31 13F BIOGEN COM 09062X103 76,350 76,350 10,020 0.0410
Disclosed Put Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share Price Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2021-05-13 2021-03-31 13F BIOGEN INC PUT COM Put 0 -100.00 0 -100.00 n/a n/a n/a
2021-02-10 2020-12-31 13F BIOGEN INC PUT COM Put 1 2 n/a n/a n/a
2020-08-14 2020-06-30 13F BIOGEN INC PUT COM Put 0 -100.00 0 -100.00 n/a n/a n/a
2020-05-18 2020-03-31 13F BIOGEN INC PUT COM Put 1 2 n/a n/a n/a
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.