Alnylam Pharmaceuticals, Inc.
DE ˙ XTRA ˙ US02043Q1076
251,80 € ↑6,70 (2,73%)
2026-06-03
DEL PRIS
SecurityDE:DUL / Alnylam Pharmaceuticals, Inc.
InstitutionSei Investments Co
Latest Disclosed Ownership111,112 shares
Latest Disclosed Value $ 44,186,866
Sei Investments Co ownership in DUL / Alnylam Pharmaceuticals, Inc.

On February 13, 2026 - Sei Investments Co filed a 13F-HR form disclosing ownership of 111,112 shares of Alnylam Pharmaceuticals, Inc. (DE:DUL) valued at $37,544,745 USD as of December 31, 2025. The entity filed a previous 13F-HR on November 13, 2025 disclosing 94,481 shares of Alnylam Pharmaceuticals, Inc.. This represents a change in shares of 17.60% during the quarter. The current value of the position is $27,978,002 USD.

Sei Investments Co has a history of taking positions in derivatives of the underlying security (DUL) 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.

DE:DUL / Alnylam Pharmaceuticals, 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)
2026-02-13 2025-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 111,112 16,631 17.60 44,187 2.56 0.0436
2025-11-13 2025-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 94,481 -214,138 -69.39 43,084 -57.19 0.0463
2025-08-14 2025-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 308,619 31,250 11.27 100,638 34.37 0.1167
2025-05-14 2025-03-31 13F/A-1 ALNYLAM PHARMACEUTICALS COM 02043Q107 277,369 11,369 4.27 74,895 19.65 0.0964
2025-05-13 2025-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 268,500 2,500 63,682 0.0693
2025-02-11 2024-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 266,000 28,093 11.81 62,595 -4.34 0.0804
2024-11-12 2024-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 237,907 198,729 507.25 65,436 587.20 0.0850
2024-08-13 2024-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 39,178 9,575 32.34 9,522 115.14 0.0135
2024-05-07 2024-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 29,603 3,354 12.78 4,427 -11.89 0.0065
2024-02-14 2023-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 26,249 947 3.74 5,023 12.12 0.0081
2023-11-14 2023-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 25,302 -4,461 -14.99 4,481 -20.75 0.0081
2023-08-11 2023-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 29,763 2,473 9.06 5,654 3.44 0.0099
2023-05-12 2023-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 27,290 -342 -1.24 5,465 -16.77 0.0102
2023-02-10 2022-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 27,632 -737 -2.60 6,567 15.66 0.0146
2022-11-14 2022-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 28,369 2,094 7.97 5,677 50.74 0.0127
2022-08-15 2022-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 26,275 -2,167 -7.62 3,766 -17.95 0.0081
2022-05-13 2022-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 28,442 3,001 11.80 4,590 3.89 0.0092
2022-02-14 2021-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 25,441 1,379 5.73 4,418 -4.06 0.0083
2021-11-12 2021-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 24,062 229 0.96 4,605 11.83 0.0097
2021-08-06 2021-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 23,833 4,618 24.03 4,118 51.17 0.0091
2021-05-12 2021-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 19,215 -2,500 -11.51 2,724 -4.69 0.0069
2021-02-08 2020-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 21,715 -1,302 -5.66 2,858 -15.02 0.0074
2020-12-04 2020-09-30 13F/A-1 ALNYLAM PHARMACEUTICALS COM 02043Q107 23,017 -7,558 -24.72 3,363 -25.70 0.0097
2020-11-06 2020-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 25,617 -4,958 3,742 9,009.9040
2020-08-17 2020-06-30 13F/A-1 ALNYLAM PHARMACEUTICALS COM 02043Q107 30,575 1,066 3.61 4,526 41.13 0.0140
2020-08-11 2020-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 33,401 3,892 3,978 10,790.5367
2020-05-14 2020-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 29,509 -678 -2.25 3,207 -7.53 0.0118
2020-02-06 2019-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 30,187 -46,616 -60.70 3,468 -43.40 0.0103
2019-11-12 2019-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 76,803 934 1.23 6,127 11.73 0.0157
2019-08-14 2019-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 75,869 20,283 36.49 5,484 5.83 0.0179
2019-05-15 2019-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 55,586 13,192 31.12 5,182 40.47 0.0174
2019-02-13 2018-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 42,394 294 0.70 3,689 0.24 0.0131
2018-11-08 2018-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 42,100 -20,328 -32.56 3,680 -40.15 0.0133
2018-08-03 2018-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 62,428 30,006 92.55 6,149 59.26 0.0209
2018-05-11 2018-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 32,422 -16,754 -34.07 3,861 -38.19 0.0148
2018-02-08 2017-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 49,176 -980 -1.95 6,247 6.01 0.0217
2017-11-06 2017-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 50,156 16 0.03 5,893 47.36 0.0209
2017-07-31 2017-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 50,140 -23,945 -32.32 3,999 5.32 0.0159
2017-05-05 2017-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 74,085 -1,930 -2.54 3,797 33.42 0.0166
2017-02-02 2016-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 76,015 -2,714 -3.45 2,846 -46.67 0.0138
2016-11-04 2016-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 78,729 36,075 84.58 5,337 125.48 0.0271
2016-08-11 2016-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 42,654 22,785 114.68 2,367 89.82 0.0142
2016-05-10 2016-03-31 13F/A-1 ALNYLAM PHARMACEUTICALS COM 02043Q107 19,869 300 1.53 1,247 -32.30 0.0078
2016-02-03 2015-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 19,569 16,273 493.72 1,842 595.09 0.0112
2015-11-02 2015-09-30 13F/A-1 ALNYLAM PHARMACEUTICALS COM 02043Q107 3,296 -5,234 -61.36 265 -74.10 0.0024
2015-10-30 2015-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 3,296 265
2015-08-07 2015-06-30 13F/A-1 ALNYLAM PHARMACEUTICALS COM 02043Q107 8,530 -24,480 -74.16 1,023 -70.32 0.0092
2015-08-04 2015-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 8,530 -24,480 1,023 0.0092
2015-05-14 2015-03-31 13F/A-1 ALNYLAM PHARMACEUTICALS COM 02043Q107 33,010 30,369 1,149.91 3,447 1,246.48 0.0299
2015-05-01 2015-03-31 13F ALMOST FAMILY PUT 02043Q107 33,010 33,010 3,447 0.0299
2015-02-10 2014-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 2,641 2,641 256 0.0023
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
(%)
2015-05-01 2015-03-31 13F ALMOST FAMILY PUT 33,010 3,447 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.