Alnylam Pharmaceuticals, Inc.
DE ˙ XTRA ˙ US02043Q1076
251,80 € ↑6,70 (2,73%)
2026-06-03
DEL PRIS
SecurityDE:DUL / Alnylam Pharmaceuticals, Inc.
InstitutionBrown Advisory Inc
Latest Disclosed Ownership133,953 shares
Latest Disclosed Value $ 44,321,136
Brown Advisory Inc reports 438.87% increase in ownership of DUL / Alnylam Pharmaceuticals, Inc.

On May 15, 2026 - Brown Advisory Inc filed a 13F-HR form disclosing ownership of 133,953 shares of Alnylam Pharmaceuticals, Inc. (DE:DUL) valued at $38,270,372 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 24,858 shares of Alnylam Pharmaceuticals, Inc.. This represents a change in shares of 438.87% during the quarter. The current value of the position is $33,729,365 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)
2026-05-15 2026-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 133,953 109,095 438.87 44,321 348.41 0.0325
2026-02-13 2025-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 24,858 -1,734 -6.52 9,885 -18.49 0.0138
2025-11-14 2025-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 26,592 -2,879 -9.77 12,126 26.18 0.0158
2025-08-13 2025-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 29,471 -1,914 -6.10 9,610 13.41 0.0127
2025-04-30 2025-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 31,385 -2,495 -7.36 8,475 6.30 0.0121
2025-02-14 2024-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 33,880 -5,243 -13.40 7,972 -25.90 0.0101
2024-11-13 2024-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 39,123 -3,234 -7.64 10,760 4.54 0.0135
2024-08-14 2024-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 42,357 -3,129 -6.88 10,293 51.42 0.0135
2024-04-24 2024-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 45,486 6,757 17.45 6,798 -8.31 0.0091
2024-02-08 2023-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 38,729 3,517 9.99 7,413 18.87 0.0104
2023-10-25 2023-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 35,212 -376 -1.06 6,236 -7.74 0.0102
2023-07-31 2023-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 35,588 4,290 13.71 6,760 7.82 0.0106
2023-05-08 2023-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 31,298 -517 -1.63 6,270 -17.08 0.0106
2023-02-13 2022-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 31,815 -1,327 -4.00 7,561 13.98 0.0140
2022-11-14 2022-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 33,142 -2,105 -5.97 6,633 29.00 0.0129
2022-11-14 2022-06-30 13F/A-2 ALNYLAM PHARMACEUTICALS COM 02043Q107 35,247 -7,361 -17.28 5,142 -26.10 0.0097
2022-09-13 2022-06-30 13F/A-1 ALNYLAM PHARMACEUTICALS COM 02043Q107 33,714 -8,013 4,917 0.0085
2022-08-02 2022-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 33,714 -8,013 4,917 0.0079
2022-11-14 2022-03-31 13F/A-2 ALNYLAM PHARMACEUTICALS COM 02043Q107 42,608 16,030 60.31 6,958 54.38 0.0104
2022-09-13 2022-03-31 13F/A-1 ALNYLAM PHARMACEUTICALS COM 02043Q107 41,727 15,149 6,814 0.0096
2022-05-09 2022-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 41,727 15,149 6,814 0.0093
2022-01-27 2021-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 26,578 26,578 4,507 0.0056
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.