Biogen Inc.
MX ˙ BMV ˙ US09062X1037
SecurityMX:BIIB / Biogen Inc.
InstitutionEastern Bank
Latest Disclosed Ownership796 shares
Latest Disclosed Value $ 145,931
Eastern Bank reports 7.01% decrease in ownership of BIIB / Biogen Inc.

On April 7, 2026 - Eastern Bank filed a 13F-HR form disclosing ownership of 796 shares of Biogen Inc. (MX:BIIB) valued at $145,931 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 14, 2026 disclosing 856 shares of Biogen Inc.. This represents a change in shares of -7.01% during the quarter.

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)
2026-04-07 2026-03-31 13F BIOGEN COM 09062X103 796 -60 -7.01 146 -3.33 0.0023
2026-01-14 2025-12-31 13F BIOGEN COM 09062X103 856 0 0.00 151 26.05 0.0026
2025-10-27 2025-09-30 13F BIOGEN COM 09062X103 856 0 0.00 120 11.21 0.0021
2025-07-24 2025-06-30 13F BIOGEN COM 09062X103 856 0 0.00 108 -8.55 0.0020
2025-05-08 2025-03-31 13F BIOGEN COM 09062X103 856 0 0.00 117 -10.00 0.0023
2025-01-13 2024-12-31 13F Biogen COM 09062X103 856 -68 -7.36 131 -27.37 0.0024
2024-10-21 2024-09-30 13F Biogen COM 09062X103 924 924 179 0.0032
2022-01-26 2021-12-31 13F BIOGEN IDEC COMMON STOCKS 09062X103 0 -760 -100.00 0 -100.00
2021-10-19 2021-09-30 13F BIOGEN IDEC COMMON STOCKS 09062X103 760 -80 -9.52 216 -25.77 0.0104
2021-07-20 2021-06-30 13F BIOGEN IDEC COMMON STOCKS 09062X103 840 0 0.00 291 23.83 0.0143
2021-04-27 2021-03-31 13F BIOGEN IDEC COMMON STOCKS 09062X103 840 -18 -2.10 235 11.90 0.0127
2021-01-20 2020-12-31 13F BIOGEN IDEC COMMON STOCKS 09062X103 858 0 0.00 210 -13.93 0.0118
2020-10-30 2020-09-30 13F BIOGEN IDEC COMMON STOCKS 09062X103 858 -46 -5.09 244 0.83 0.0149
2020-09-01 2020-06-30 13F/A-1 BIOGEN IDEC COMMON STOCKS 09062X103 904 -689 -43.25 242 -51.98 0.0157
2020-07-21 2020-06-30 13F BIOGEN IDEC COMMON STOCKS 09062X103 904 -689 242 15,740.9841
2020-04-27 2020-03-31 13F BIOGEN IDEC COMMON STOCKS 09062X103 1,593 383 31.65 504 40.39 0.0375
2020-02-04 2019-12-31 13F BIOGEN IDEC COMMON STOCKS 09062X103 1,210 0 0.00 359 27.30 0.0209
2019-11-04 2019-09-30 13F BIOGEN IDEC COMMON STOCKS 09062X103 1,210 -66 -5.17 282 -5.37 0.0176
2019-07-24 2019-06-30 13F BIOGEN IDEC COMMON STOCKS 09062X103 1,276 -55 -4.13 298 -5.10 0.0190
2019-04-18 2019-03-31 13F BIOGEN IDEC COMMON STOCKS 09062X103 1,331 -86 -6.07 314 -26.29 0.0210
2019-01-18 2018-12-31 13F BIOGEN IDEC COMMON STOCKS 09062X103 1,417 -17 -1.19 426 -15.81 0.0318
2018-10-16 2018-09-30 13F BIOGEN IDEC COMMON STOCKS 09062X103 1,434 -119 -7.66 506 12.20 0.0330
2018-07-18 2018-06-30 13F BIOGEN IDEC COMMON STOCKS 09062X103 1,553 0 0.00 451 6.37 0.0308
2018-04-09 2018-03-31 13F BIOGEN IDEC COMMON STOCKS 09062X103 1,553 -46 -2.88 424 -16.86 0.0297
2018-01-22 2017-12-31 13F BIOGEN IDEC COMMON STOCKS 09062X103 1,599 -182 -10.22 510 -8.60 0.0342
2017-10-24 2017-09-30 13F BIOGEN IDEC COMMON STOCKS 09062X103 1,781 -58 -3.15 558 11.82 0.0395
2017-07-26 2017-06-30 13F BIOGEN IDEC COMMON STOCKS 09062X103 1,839 -215 -10.47 499 -11.05 0.0367
2017-04-17 2017-03-31 13F BIOGEN IDEC COMMON STOCKS 09062X103 2,054 -312 -13.19 561 -16.52 0.0423
2017-01-18 2016-12-31 13F BIOGEN IDEC COMMON STOCKS 09062X103 2,366 -1,381 -36.86 672 -42.71 0.0523
2016-10-17 2016-09-30 13F BIOGEN IDEC COMMON STOCKS 09062X103 3,747 -881 -19.04 1,173 4.83 0.0943
2016-07-15 2016-06-30 13F BIOGEN IDEC COMMON STOCKS 09062X103 4,628 -43,978 -90.48 1,119 -91.16 0.0904
2016-04-14 2016-03-31 13F BIOGEN IDEC COMMON STOCKS 09062X103 48,606 9,207 23.37 12,653 4.84 1.0319
2016-01-20 2015-12-31 13F BIOGEN IDEC COMMON STOCKS 09062X103 39,399 143 0.36 12,069 5.36 1.0047
2015-10-16 2015-09-30 13F BIOGEN IDEC COMMON STOCKS 09062X103 39,256 171 0.44 11,455 -27.45 0.9987
2015-07-16 2015-06-30 13F BIOGEN IDEC COMMON STOCKS 09062X103 39,085 776 2.03 15,789 -2.39 1.2752
2015-04-17 2015-03-31 13F BIOGEN IDEC COMMON STOCKS 09062X103 38,309 -11,852 -23.63 16,175 -5.01 1.2955
2015-01-12 2014-12-31 13F BIOGEN IDEC COMMON STOCKS 09062X103 50,161 468 0.94 17,028 3.58 1.3514
2014-10-15 2014-09-30 13F BIOGEN IDEC COMMON STOCKS 09062X103 49,693 682 1.39 16,439 6.37 1.3286
2014-07-16 2014-06-30 13F BIOGEN IDEC COMMON STOCKS 09062X103 49,011 12,655 34.81 15,454 38.97 1.2515
2014-04-17 2014-03-31 13F BIOGEN IDEC COMMON STOCKS 09062X103 36,356 -1,294 -3.44 11,120 5.65 0.9368
2014-01-21 2013-12-31 13F BIOGEN IDEC COMMON STOCKS 09062X103 37,650 -12,408 -24.79 10,525 -12.67 0.8968
2013-10-18 2013-09-30 13F BIOGEN IDEC COMMON STOCKS 09062X103 50,058 -2,495 -4.75 12,052 6.57 1.1053
2013-08-09 2013-06-30 13F BIOGEN IDEC COMMON STOCKS 09062X103 52,553 52,553 11,309 1.0520
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.