Alnylam Pharmaceuticals, Inc.
US ˙ NasdaqGS ˙ US02043Q1076

SecurityALNY / Alnylam Pharmaceuticals, Inc.
InstitutionDriehaus Capital Management Llc
Latest Disclosed Ownership59,622 shares
Latest Disclosed Value $ 19,727,131
Driehaus Capital Management Llc reports 14.55% decrease in ownership of ALNY / Alnylam Pharmaceuticals, Inc.

On May 15, 2026 - Driehaus Capital Management Llc filed a 13F-HR form disclosing ownership of 59,622 shares of Alnylam Pharmaceuticals, Inc. (US:ALNY) valued at $19,727,131 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 69,778 shares of Alnylam Pharmaceuticals, Inc.. This represents a change in shares of -14.55% during the quarter. The current value of the position is $17,444,205 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 59,622 -10,156 -14.55 19,727 -28.90 0.1445
2026-02-17 2025-12-31 13F Alnylam Pharmaceuticals COM 02043Q107 69,778 8,399 13.68 27,747 -0.86 0.1885
2025-11-14 2025-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 61,379 -18,335 -23.00 27,989 7.68 0.2005
2025-08-14 2025-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 79,714 22,586 39.54 25,994 68.51 0.2080
2025-05-15 2025-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 57,128 23,648 70.63 15,426 95.80 0.1487
2025-02-14 2024-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 33,480 1,130 3.49 7,878 -11.45 0.0650
2024-11-14 2024-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 32,350 -139 -0.43 8,897 12.71 0.0764
2024-08-15 2024-06-30 13F/A-1 ALNYLAM PHARMACEUTICALS COM 02043Q107 32,489 32,489 7,895 0.0764
2024-08-14 2024-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 32,489 32,489 7,895 0.0761
2024-05-15 2024-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 0 -38,988 -100.00 0 -100.00
2024-02-14 2023-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 38,988 -41 -0.11 7,463 7.96 0.0899
2023-11-14 2023-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 39,029 -9 -0.02 6,912 -6.77 0.0899
2023-08-14 2023-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 39,038 2,778 7.66 7,415 2.08 0.0936
2023-05-15 2023-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 36,260 -32,991 -47.64 7,264 -55.87 0.1019
2023-02-14 2022-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 69,251 1,169 1.72 16,458 20.77 0.2454
2022-11-14 2022-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 68,082 11,812 20.99 13,627 66.04 0.2063
2022-08-15 2022-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 56,270 1,821 3.34 8,207 -7.69 0.1329
2022-05-16 2022-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 54,449 -8,562 -13.59 8,891 -16.79 0.1092
2022-02-14 2021-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 63,011 18,509 41.59 10,685 27.17 0.1090
2021-11-15 2021-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 44,502 41,723 1,501.37 8,402 1,683.86 0.0996
2021-08-16 2021-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 2,779 -29 -1.03 471 18.94 0.0062
2021-05-17 2021-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 2,808 -813 -22.45 396 -15.92 0.0058
2021-02-16 2020-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 3,621 31 0.86 471 -9.94 0.0076
2020-11-16 2020-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 3,590 438 13.90 523 11.99 0.0107
2020-08-14 2020-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 3,152 172 5.77 467 44.14 0.0114
2020-05-15 2020-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 2,980 699 30.64 324 23.19 0.0108
2020-02-12 2019-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 2,281 2,281 263 0.0070
2019-02-14 2018-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 0 -4,843 -100.00 0 -100.00
2018-11-14 2018-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 4,843 95 2.00 424 -9.40 0.0131
2018-08-14 2018-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 4,748 -600 -11.22 468 -26.53 0.0158
2018-05-15 2018-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 5,348 -25 -0.47 637 -6.73 0.0225
2018-02-14 2017-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 5,373 -6,436 -54.50 683 -50.76 0.0259
2017-11-14 2017-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 11,809 1,926 19.49 1,387 76.02 0.0541
2017-08-14 2017-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 9,883 9,883 788 0.0290
2017-02-14 2016-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 0 -8,102 -100.00 0 -100.00
2016-11-14 2016-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 8,102 111 1.39 549 23.93 0.0186
2016-08-15 2016-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 7,991 7,991 0.00 443 0.0158
2016-05-13 2016-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 0 -8,993 -100.00 0 -100.00
2016-02-12 2015-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 8,993 5,928 193.41 847 244.31 0.0286
2015-11-16 2015-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 3,065 -24,083 -88.71 246 -92.44 0.0089
2015-08-24 2015-06-30 13F/A-1 ALNYLAM PHARMACEUTICALS COM 02043Q107 27,148 -1,978 -6.79 3,254 7.00 0.1199
2015-08-14 2015-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 27,023 3,239
2015-05-15 2015-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 29,126 -22,640 -43.74 3,041 -39.43 0.1054
2015-02-13 2014-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 51,766 -40,554 -43.93 5,021 -30.36 0.2021
2014-11-14 2014-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 92,320 -46,806 -33.64 7,210 -17.97 0.2748
2014-08-14 2014-06-30 13F Alnylam Pharmaceuticals COM 02043Q107 139,126 -70,215 -33.54 8,789 -37.47 0.2851
2014-05-15 2014-03-31 13F Alnylam Pharmaceuticals COM 02043Q107 209,341 82,915 65.58 14,055 72.81 0.4421
2014-02-13 2013-12-31 13F Alnylam Pharmaceuticals COM 02043Q107 126,426 -130,834 -50.86 8,133 -50.61 0.2935
2013-11-14 2013-09-30 13F Alnylam Pharmaceuticals COM 02043Q107 257,260 -70,871 -21.60 16,467 61.84 0.6359
2013-08-14 2013-06-30 13F Alnylam Pharmaceuticals COM 02043Q107 328,131 328,131 10,175 0.4446
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.