Ionis Pharmaceuticals, Inc.
MX ˙ BMV ˙ US4622221004
SecurityMX:IONS / Ionis Pharmaceuticals, Inc.
InstitutionJanus Henderson Group Plc
Latest Disclosed Ownership68,191 shares
Latest Disclosed Value $ 5,120,803
Janus Henderson Group Plc ownership in IONS / Ionis Pharmaceuticals, Inc.

On May 18, 2026 - Janus Henderson Group Plc filed a 13F-HR/A form disclosing ownership of 68,191 shares of Ionis Pharmaceuticals, Inc. (MX:IONS) valued at $5,120,803 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 68,191 shares of Ionis Pharmaceuticals, Inc.. This represents a change in shares of 0.00% 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.

Upgrade to unlock premium data and export to Excel .

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 IONIS PHARMACEUTICALS COM 462222100 68,191 0 0.00 5,121 -5.10 0.0009
2026-05-15 2026-03-31 13F IONIS PHARMACEUTICALS COM 462222100 68,191 0 5,121 0.0010
2026-02-17 2025-12-31 13F IONIS PHARMACEUTICALS COM 462222100 68,191 4,314 6.75 5,396 29.13 0.0024
2025-11-14 2025-09-30 13F IONIS PHARMACEUTICALS COM 462222100 63,877 0 0.00 4,179 65.60 0.0019
2025-08-14 2025-06-30 13F IONIS PHARMACEUTICALS COM 462222100 63,877 0 0.00 2,523 26.78 0.0012
2025-05-15 2025-03-31 13F IONIS PHARMACEUTICALS COM 462222100 63,877 0 0.00 1,990 -10.84 0.0011
2025-02-14 2024-12-31 13F IONIS PHARMACEUTICALS COM 462222100 63,877 4,900 8.31 2,233 -5.50 0.0011
2024-11-14 2024-09-30 13F IONIS PHARMACEUTICALS COM 462222100 58,977 0 0.00 2,363 -16.00 0.0012
2024-08-14 2024-06-30 13F IONIS PHARMACEUTICALS COM 462222100 58,977 -740 -1.24 2,813 8.66 0.0015
2024-05-15 2024-03-31 13F IONIS PHARMACEUTICALS COM 462222100 59,717 14 0.02 2,589 -14.28 0.0014
2024-02-14 2023-12-31 13F IONIS PHARMACEUTICALS COM 462222100 59,703 -103 -0.17 3,019 11.36 0.0018
2023-11-14 2023-09-30 13F IONIS PHARMACEUTICALS COM 462222100 59,806 4 0.01 2,712 10.52 0.0018
2023-08-14 2023-06-30 13F IONIS PHARMACEUTICALS COM 462222100 59,802 -57 -0.10 2,454 14.63 0.0015
2023-05-15 2023-03-31 13F IONIS PHARMACEUTICALS COM 462222100 59,859 6,137 11.42 2,141 5.52 0.0014
2023-02-14 2022-12-31 13F IONIS PHARMACEUTICALS COM 462222100 53,722 30,582 132.16 2,029 98.24 0.0014
2023-01-13 2022-09-30 13F/A-1 IONIS PHARMACEUTICALS COM 462222100 23,140 -67 -0.29 1,023 19.23 0.0008
2022-11-14 2022-09-30 13F IONIS PHARMACEUTICALS COM 462222100 23,140 -67 1,023 0.0008
2022-08-15 2022-06-30 13F IONIS PHARMACEUTICALS COM 462222100 23,207 -2,516 -9.78 858 -9.97 0.0006
2022-05-16 2022-03-31 13F IONIS PHARMACEUTICALS COM 462222100 25,723 7 0.03 953 21.71 0.0005
2022-02-14 2021-12-31 13F IONIS PHARMACEUTICALS COM 462222100 25,716 11,968 87.05 783 69.85 0.0003
2021-11-16 2021-09-30 13F IONIS PHARMACEUTICALS COM 462222100 13,748 13,748 461 0.0002
2021-08-16 2021-06-30 13F IONIS PHARMACEUTICALS COM 462222100 0 -76,644 -100.00 0 -100.00
2021-05-17 2021-03-31 13F IONIS PHARMACEUTICALS COM 462222100 76,644 26,018 51.39 3,446 20.41 0.0016
2021-02-16 2020-12-31 13F IONIS PHARMACEUTICALS COM 462222100 50,626 -10,053 -16.57 2,862 -0.59 0.0013
2020-11-16 2020-09-30 13F IONIS PHARMACEUTICALS COM 462222100 60,679 -8,848 -12.73 2,879 -29.76 0.0015
2020-08-14 2020-06-30 13F IONIS PHARMACEUTICALS COM 462222100 69,527 22,253 47.07 4,099 83.32 0.0023
2020-05-14 2020-03-31 13F IONIS PHARMACEUTICALS COM 462222100 47,274 -154,438 -76.56 2,236 -81.65 0.0015
2020-02-18 2019-12-31 13F IONIS PHARMACEUTICALS COM 462222100 201,712 -380,819 -65.37 12,185 -65.09 0.0062
2019-11-14 2019-09-30 13F IONIS PHARMACEUTICALS COM 462222100 582,531 274,852 89.33 34,900 76.49 0.0189
2019-07-31 2019-06-30 13F IONIS PHARMACEUTICALS COM 462222100 307,679 211,161 218.78 19,775 152.43 0.0108
2019-04-30 2019-03-31 13F IONIS PHARMACEUTICALS COM 462222100 96,518 84,587 708.97 7,834 1,114.57 0.0043
2019-02-06 2018-12-31 13F IONIS PHARMACEUTICALS COM 462222100 11,931 11,931 645 0.0004
2018-08-10 2018-06-30 13F IONIS PHARMACEUTICALS COM 462222100 0 -14,300 -100.00 0 -100.00
2018-05-14 2018-03-31 13F IONIS PHARMACEUTICALS COM 462222100 14,300 14,300 630 0.0004
2016-10-24 2016-09-30 13F IONIS PHARMACEUTICALS COM 462222100 0 -12,763 -100.00 0 -100.00
2016-07-29 2016-06-30 13F IONIS PHARMACEUTICALS COM 462222100 12,763 0 0.00 297 -42.55 0.0025
2016-05-12 2016-03-31 13F IONIS PHARMACEUTICALS COM 462222100 12,763 0 0.00 517 -34.64 0.0042
2016-02-03 2015-12-31 13F IONIS PHARMACEUTICALS COM 462222100 12,763 0 0.00 791 53.29 0.0063
2015-11-16 2015-09-30 13F ISIS PHARMACEUTICALS COM 464330109 12,763 0 0.00 516 -29.70 0.0045
2015-08-17 2015-06-30 13F ISIS PHARMACEUTICALS COM 464330109 12,763 0 0.00 734 -9.61 0.0058
2015-06-02 2015-03-31 13F/A-1 ISIS PHARMACEUTICALS COM 464330109 12,763 12,763 812 0.0063
2015-05-15 2015-03-31 13F ISIS PHARMACEUTICALS COM 464330109 12,763 812 0.0065
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.