Alnylam Pharmaceuticals, Inc.
DE ˙ XTRA ˙ US02043Q1076
260,50 € ↑8,70 (3,46%)
2026-06-04
DEL PRIS
SecurityDE:DUL / Alnylam Pharmaceuticals, Inc.
InstitutionPortman Square Capital LLP
Latest Disclosed Ownership16,924 shares
Latest Disclosed Value $ 5,599,644
Portman Square Capital LLP ownership in DUL / Alnylam Pharmaceuticals, Inc.

On April 27, 2026 - Portman Square Capital LLP filed a 13F-HR form disclosing ownership of 16,924 shares of Alnylam Pharmaceuticals, Inc. (DE:DUL) valued at $4,835,187 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 23, 2026 disclosing 2,457 shares of Alnylam Pharmaceuticals, Inc.. This represents a change in shares of 588.81% during the quarter. The current value of the position is $4,408,702 USD.

Portman Square Capital LLP 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)
2026-04-27 2026-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 16,924 14,467 588.81 5,600 473.08 0.2156
2026-01-23 2025-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 2,457 2,457 977 0.0432
2025-10-16 2025-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 0 -6,967 -100.00 0 -100.00
2025-07-29 2025-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 6,967 -5,562 -44.39 2,272 -32.87 0.0664
2025-05-02 2025-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 12,529 -410 -3.17 3,383 11.14 0.0899
2025-01-16 2024-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 12,939 4,426 51.99 3,045 30.03 0.1091
2024-10-16 2024-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 8,513 -3,335 -28.15 2,341 -18.69 0.0872
2024-07-19 2024-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 11,848 -4,175 -26.06 2,879 20.26 0.0987
2024-04-15 2024-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 16,023 10,060 168.71 2,395 109.82 0.0663
2024-01-19 2023-12-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 5,963 -5,951 -49.95 1,141 -45.90 0.0261
2023-10-30 2023-09-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 11,914 2,146 21.97 2,110 13.69 0.0519
2023-07-26 2023-06-30 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 9,768 4,876 99.67 1,855 89.48 0.0528
2023-05-04 2023-03-31 13F ALNYLAM PHARMACEUTICALS COM 02043Q107 4,892 4,892 980 0.0450
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
(%)
2026-04-27 2026-03-31 13F ALNYLAM PHARMACEUTICALS COM Put 37,900 30.69 12,540 8.74 n/a n/a n/a
2026-01-23 2025-12-31 13F ALNYLAM PHARMACEUTICALS COM Put 29,000 16.00 11,532 1.15 n/a n/a n/a
2025-10-16 2025-09-30 13F ALNYLAM PHARMACEUTICALS COM Put 25,000 -30.56 11,400 -2.89 n/a n/a n/a
2025-07-29 2025-06-30 13F ALNYLAM PHARMACEUTICALS COM Put 36,000 0.00 11,739 20.77 n/a n/a n/a
2025-05-02 2025-03-31 13F ALNYLAM PHARMACEUTICALS COM Put 36,000 -13.46 9,721 -0.69 n/a n/a n/a
2025-01-16 2024-12-31 13F ALNYLAM PHARMACEUTICALS COM Put 41,600 31.65 9,789 12.64 n/a n/a n/a
2024-10-16 2024-09-30 13F ALNYLAM PHARMACEUTICALS COM Put 31,600 -43.87 8,691 -36.48 n/a n/a n/a
2024-07-19 2024-06-30 13F ALNYLAM PHARMACEUTICALS COM Put 56,300 0.00 13,681 62.59 n/a n/a n/a
2024-04-15 2024-03-31 13F ALNYLAM PHARMACEUTICALS COM Put 56,300 10.39 8,414 -13.80 n/a n/a n/a
2024-01-19 2023-12-31 13F ALNYLAM PHARMACEUTICALS COM Put 51,000 0.00 9,762 8.07 n/a n/a n/a
2023-10-30 2023-09-30 13F ALNYLAM PHARMACEUTICALS COM Put 51,000 142.86 9,032 126.48 n/a n/a n/a
2023-07-26 2023-06-30 13F ALNYLAM PHARMACEUTICALS COM Put 21,000 -61.11 3,989 -63.13 n/a n/a n/a
2023-05-04 2023-03-31 13F ALNYLAM PHARMACEUTICALS COM Put 54,000 80.00 10,817 51.73 n/a n/a n/a
2023-02-23 2022-12-31 13F ALNYLAM PHARMACEUTICALS COM Put 30,000 7,130 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.