Ionis Pharmaceuticals, Inc. (IONS) Ownership
IONS ownership summary
as of October 18, 2026- Institutions
- 110.2% of shares outstanding
- Insiders
- 0.61% of shares outstanding
- Shares outstanding
- 166.2M
- Float
- 164.8M shares available to trade
- Short interest
- 17.94% 22.5M shares short
- Days to cover
- 5.07 short interest up 7.7% vs prior month
- Institutions 110.25%
- Insiders 0.61%
IONS top institutional holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | FMR Inc | 14.82% | 24.6M | $1.06B | +75,319 (+0.3%) | June 30, 2026 |
| 2 | Capital World Investors | 13.04% | 21.7M | $930.5M | +482,857 (+2.3%) | June 30, 2026 |
| 3 | BlackRock Inc | 6.44% | 10.7M | $459.7M | +262,184 (+2.5%) | June 30, 2026 |
| 4 | Vanguard Portfolio Management, LLC | 4.73% | 7.9M | $337.5M | +50,627 (+0.6%) | June 30, 2026 |
| 5 | Wellington Management Company LLP | 4.60% | 7.7M | $328.6M | +1.3M (+19.7%) | June 30, 2026 |
| 6 | Vanguard Capital Management, LLC | 4.34% | 7.2M | $309.7M | +93,167 (+1.3%) | June 30, 2026 |
| 7 | Two Sigma Investments LLC | 3.76% | 6.3M | $268.5M | +394,713 (+6.7%) | June 30, 2026 |
| 8 | Royal Bank of Canada | 3.72% | 6.2M | $265.5M | +2.4M (+62.6%) | June 30, 2026 |
| 9 | State Street Corp | 2.61% | 4.3M | $186.1M | +339,284 (+8.5%) | June 30, 2026 |
| 10 | T. Rowe Price Investment Management,Inc. | 2.38% | 4.0M | $170.0M | −2.2M (−35.7%) | June 30, 2026 |
| 11 | Geode Capital Management, LLC | 2.16% | 3.6M | $153.9M | −400,308 (−10.0%) | June 30, 2026 |
| 12 | T. Rowe Price Associates, Inc. | 1.92% | 3.2M | $136.7M | +159,249 (+5.3%) | June 30, 2026 |
| 13 | JPMorgan Chase & Co | 1.61% | 2.7M | $114.7M | +308,150 (+13.0%) | June 30, 2026 |
| 14 | Artisan Partners Limited Partnership | 1.59% | 2.6M | $113.4M | +581,716 (+28.3%) | June 30, 2026 |
| 15 | Tweedy, Browne Co LLC | 1.37% | 2.3M | $97.9M | +4,686 (+0.2%) | June 30, 2026 |
| 16 | Deep Track Capital, LP | 1.32% | 2.2M | $94.5M | +250,000 (+12.8%) | June 30, 2026 |
| 17 | The Goldman Sachs Group Inc | 1.27% | 2.1M | $90.6M | +410,098 (+24.1%) | June 30, 2026 |
| 18 | Baker Bros Advisors LP | 1.23% | 2.0M | $87.9M | — | June 30, 2026 |
| 19 | Deerfield Management Co | 1.19% | 2.0M | $85.0M | — | June 30, 2026 |
| 20 | American Century Companies Inc | 1.17% | 1.9M | $83.6M | +283,273 (+17.0%) | June 30, 2026 |
Value at the latest close. Change = shares bought or sold in the latest quarterly filing (13F). In the top 20, 16 holders added 7.3M shares and 2 cut 2.6M.
IONS top mutual fund and ETF holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | Fidelity Growth Company Fund | 5.12% | 8.5M | $365.1M | +400 (+0.0%) | August 31, 2026 |
| 2 | American Funds Growth Fd of Amer A | 4.61% | 7.7M | $329.3M | — | September 30, 2026 |
| 3 | Vanguard MStar Total Stk Mkt Idx Invest | 3.01% | 5.0M | $214.7M | −6,061 (−0.1%) | August 31, 2026 |
| 4 | American Funds New Economy A | 2.93% | 4.9M | $209.1M | — | September 30, 2026 |
| 5 | Vanguard Health Care Inv | 2.73% | 4.5M | $194.5M | +727,496 (+19.1%) | June 30, 2026 |
| 6 | American Funds SMALLCAP World A | 2.68% | 4.5M | $191.4M | −801,774 (−15.2%) | September 30, 2026 |
| 7 | Vanguard Small Cap Index | 2.14% | 3.6M | $152.5M | −61,481 (−1.7%) | September 30, 2026 |
| 8 | State Street® SPDR® S&P® Biotech ETF | 1.60% | 2.7M | $114.0M | −50,550 (−1.9%) | September 30, 2026 |
| 9 | Fidelity Growth Company K6 | 1.44% | 2.4M | $102.7M | +114 (+0.0%) | August 31, 2026 |
| 10 | Fidelity Series Growth Company | 1.20% | 2.0M | $85.6M | +100 (+0.0%) | August 31, 2026 |
| 11 | Vanguard MStar Small Cap Growth Indx Inv | 1.19% | 2.0M | $84.8M | −99,565 (−4.8%) | September 30, 2026 |
| 12 | American Funds IS® Growth 1 | 1.01% | 1.7M | $71.9M | — | September 30, 2026 |
| 13 | T. Rowe Price Mid-Cap Growth | 0.95% | 1.6M | $68.1M | — | September 30, 2026 |
| 14 | Tweedy, Browne International Value Fund | 0.93% | 1.5M | $66.2M | −201,500 (−11.6%) | September 30, 2026 |
| 15 | Vanguard Explorer Inv | 0.85% | 1.4M | $60.5M | +212,851 (+17.8%) | June 30, 2026 |
| 16 | Capital Group Growth ETF | 0.81% | 1.3M | $57.8M | +3,528 (+0.3%) | September 30, 2026 |
| 17 | iShares Biotechnology ETF | 0.77% | 1.3M | $54.6M | −9,632 (−0.8%) | September 30, 2026 |
| 18 | Polar Capital Biotech S Inc | 0.69% | 1.2M | $49.4M | — | August 31, 2026 |
| 19 | Pictet-Biotech P USD | 0.64% | 1.1M | $45.6M | −11,971 (−1.1%) | August 31, 2026 |
| 20 | Schwab US Small-Cap ETF™ | 0.53% | 875K | $37.6M | +585 (+0.1%) | September 30, 2026 |
Funds report holdings monthly or quarterly; dates differ by fund.
IONS insider transactions
latest 20| Date | Name | Transaction | Price | Shares | Value |
|---|---|---|---|---|---|
| 2026-04-16 | Kyle Jenne | Sell | $75.17 | 4,902 | $368,483 |
| 2026-04-16 | Brian Birchler | Sell | $75.04 | 973 | $73,014 |
| 2026-04-15 | B Lynne Parshall | Sell | $76.27 | 5,000 | $381,350 |
| 2026-04-02 | Shannon L Devers | Sell | $74.05 | 6,193 | $458,592 |
| 2026-03-19 | Eugene Schneider | Sell | $70.97 | 5,812 | $412,478 |
| 2026-03-17 | Elizabeth L Hougen | Sell | $73.21 | 10,172 | $744,692 |
| 2026-03-16 | Elizabeth L Hougen | Sell | $72.40 | 215,048 | $15.6M |
| 2026-03-10 | Brett P Monia | Sell | $75.92 | 34,103 | $2.6M |
| 2026-03-10 | Kyle Jenne | Sell | $75.85 | 37,277 | $2.8M |
| 2026-03-09 | Patrick R O'neil | Sell | $75.25 | 10,148 | $763,637 |
| 2026-03-09 | Brett P Monia | Sell | $75.20 | 126,670 | $9.5M |
| 2026-03-03 | Allene M Diaz | Sell | $79.35 | 54,878 | $4.4M |
| 2026-03-03 | C Frank Bennett | Sell | $79.23 | 85,089 | $6.7M |
| 2026-03-03 | Shannon L Devers | Sell | $79.40 | 20,106 | $1.6M |
| 2026-02-13 | Eric Swayze | Sell | $81.76 | 15,642 | $1.3M |
| 2026-02-11 | B Lynne Parshall | Sell | $82.72 | 5,000 | $413,600 |
| 2026-02-06 | Brett P Monia | Sell | $85.79 | 29,430 | $2.5M |
| 2026-02-02 | C Frank Bennett | Sell | $82.93 | 85,089 | $7.1M |
| 2026-01-30 | Brett P Monia | Sell | $82.72 | 62,970 | $5.2M |
| 2026-01-30 | Brian Birchler | Sell | $83.03 | 6,179 | $513,042 |
Reported trades by company officers, directors and other filers (including disclosures by members of Congress where EODHD lists them). "—" where the filing gives no share count.
IONS shares outstanding
Year-end shares outstanding, adjusted for splits.
Who owns IONS
Institutional investors own 110.2% of Ionis Pharmaceuticals's shares and insiders 0.61%. The largest holder is FMR Inc with 14.82% of the shares (24.6M), as of June 30, 2026. Among the top 20 institutions, 16 added shares and 2 reduced their stake in the latest filings. Short interest is 17.94% of the float, or 5.07 days of average trading volume. The share count rose 31.9% since 2014.
Related: IONS analyst forecast, IONS key metrics. See the IONS stock overview for the latest quote and news.
IONS ownership FAQ
Who owns the most Ionis Pharmaceuticals stock?
The largest shareholders of Ionis Pharmaceuticals are FMR Inc (14.82%), Capital World Investors (13.04%), BlackRock Inc (6.44%), Vanguard Portfolio Management, LLC (4.73%), Wellington Management Company LLP (4.60%).
What percentage of Ionis Pharmaceuticals is owned by institutions?
Institutions hold 110.2% of Ionis Pharmaceuticals's shares outstanding; insiders hold 0.61%.
Which funds own Ionis Pharmaceuticals?
The largest fund holders of Ionis Pharmaceuticals are Fidelity Growth Company Fund (5.12%), American Funds Growth Fd of Amer A (4.61%), Vanguard MStar Total Stk Mkt Idx Invest (3.01%), American Funds New Economy A (2.93%), Vanguard Health Care Inv (2.73%).
What is Ionis Pharmaceuticals's short interest?
22.5M shares of Ionis Pharmaceuticals were sold short, 17.94% of the float; at the average daily volume it would take 5.07 days to cover.
Are insiders buying or selling Ionis Pharmaceuticals?
Of the latest 20 reported insider transactions in Ionis Pharmaceuticals (since January 30, 2026), 0 were purchases and 20 were sales.
How many shares of Ionis Pharmaceuticals are outstanding?
Ionis Pharmaceuticals has 166.2M shares outstanding, of which 164.8M are in the public float.