Arrowhead Pharmaceuticals, Inc.
MX ˙ BMV ˙ US04280A1007
SecurityMX:ARWR / Arrowhead Pharmaceuticals, Inc.
InstitutionJanus Henderson Group Plc
Latest Disclosed Ownership1,436,990 shares
Latest Disclosed Value $ 90,119,095
Janus Henderson Group Plc reports 12.23% increase in ownership of ARWR / Arrowhead Pharmaceuticals, Inc.

On May 18, 2026 - Janus Henderson Group Plc filed a 13F-HR/A form disclosing ownership of 1,436,990 shares of Arrowhead Pharmaceuticals, Inc. (MX:ARWR) valued at $90,119,095 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 1,280,446 shares of Arrowhead Pharmaceuticals, Inc.. This represents a change in shares of 12.23% 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)
2026-05-18 2026-03-31 13F/A-1 ARROWHEAD PHARMACEUTICALS IN COM 04280A100 1,436,990 156,544 12.23 90,119 6.03 0.0152
2026-05-15 2026-03-31 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 1,436,990 156,544 12.23 90,119 6.03 0.0167
2026-02-17 2025-12-31 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 1,280,446 306,879 31.52 84,997 153.47 0.0381
2025-11-14 2025-09-30 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 973,567 923,722 1,853.19 33,535 4,160.99 0.0153
2025-08-14 2025-06-30 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 49,845 0 0.00 788 14.39 0.0004
2025-05-15 2025-03-31 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 49,845 0 0.00 689 -26.50 0.0004
2025-02-14 2024-12-31 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 49,845 0 0.00 937 -2.90 0.0005
2024-11-14 2024-09-30 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 49,845 -7,000 -12.31 965 -34.64 0.0005
2024-08-14 2024-06-30 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 56,845 -604 -1.05 1,476 -10.12 0.0008
2024-05-15 2024-03-31 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 57,449 10,082 21.28 1,641 13.25 0.0009
2024-02-14 2023-12-31 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 47,367 -91 -0.19 1,450 13.83 0.0009
2023-11-14 2023-09-30 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 47,458 5 0.01 1,274 -24.72 0.0008
2023-08-14 2023-06-30 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 47,453 -594,604 -92.61 1,692 -89.63 0.0011
2023-05-15 2023-03-31 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 642,057 76,149 13.46 16,309 -28.95 0.0108
2023-02-14 2022-12-31 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 565,908 -3,325 -0.58 22,953 22.00 0.0164
2023-01-13 2022-09-30 13F/A-1 ARROWHEAD PHARMACEUTICALS IN COM 04280A100 569,233 -2,197 -0.38 18,813 -6.50 0.0141
2022-11-14 2022-09-30 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 569,233 -2,197 18,813 0.0141
2022-08-15 2022-06-30 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 571,430 -160,134 -21.89 20,120 -40.20 0.0139
2022-05-16 2022-03-31 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 731,564 -235,121 -24.32 33,645 -47.50 0.0162
2022-02-14 2021-12-31 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 966,685 6,453 0.67 64,090 6.91 0.0267
2021-11-16 2021-09-30 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 960,232 -181,363 -15.89 59,948 -36.59 0.0262
2021-08-16 2021-06-30 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 1,141,595 1,282 0.11 94,547 25.04 0.0405
2021-05-17 2021-03-31 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 1,140,313 -5,130 -0.45 75,614 -13.97 0.0345
2021-02-16 2020-12-31 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 1,145,443 -13,019 -1.12 87,890 76.19 0.0408
2020-11-16 2020-09-30 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 1,158,462 230,663 24.86 49,883 24.48 0.0260
2020-08-14 2020-06-30 13F ARROWHEAD PHARMACEUTICALS IN COM 04280A100 927,799 927,799 40,072 0.0225
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.