Ranked by reported Q1 2026 13F market value
Share of total reported institutional value in IONS held by the largest 10 / 25 filers.
| # | Institution | Shares Held | Market Value | QoQ Change | Ownership % | % of Fund |
|---|---|---|---|---|---|---|
| 1 | FMR LLC | 24.6M | $1.84B | +2.0% | 14.859% | 0.10% |
| 2 | Capital World Investors | 21.2M | $1.59B | +18.0% | 12.820% | 0.22% |
| 3 | BlackRock, Inc. | 10.4M | $784.1M | -1.9% | 6.319% | 0.01% |
| 4 | VANGUARD PORTFOLIO MANAGEMENT LLC | 7.8M | $586.4M | — | 4.725% | 0.03% |
| 5 | VANGUARD CAPITAL MANAGEMENT LLC | 7.1M | $534.5M | — | 4.307% | 0.01% |
| 6 | WELLINGTON MANAGEMENT GROUP LLP | 6.4M | $480.0M | +2.1% | 3.868% | 0.09% |
| 7 | TWO SIGMA INVESTMENTS, LP | 5.9M | $439.8M | +120.3% | 3.544% | 0.36% |
| 8 | GEODE CAPITAL MANAGEMENT, LLC | 4.0M | $305.2M | +26.5% | 2.411% | 0.02% |
| 9 | STATE STREET CORP | 4.0M | $300.0M | +0.5% | 2.418% | 0.01% |
| 10 | ROYAL BANK OF CANADA | 3.8M | $285.5M | +219.2% | 2.300% | 0.05% |
| 11 | Tweedy, Browne Co LLC | 2.3M | $170.9M | -7.7% | 1.377% | 13.57% |
| 12 | Artisan Partners Limited Partnership | 2.1M | $154.6M | +74.2% | 1.246% | 0.25% |
| 13 | BAKER BROS. ADVISORS LP | 2.0M | $153.8M | +14.3% | 1.239% | 0.88% |
| 14 | DEERFIELD MANAGEMENT COMPANY, L.P. (SERIES C) | 2.0M | $148.7M | 0.0% | 1.198% | 1.75% |
| 15 | Deep Track Capital, LP | 1.9M | $146.4M | +14.7% | 1.180% | 3.02% |
| 16 | Bellevue Group AG | 1.8M | $136.6M | -62.1% | 1.100% | 3.25% |
| 17 | GOLDMAN SACHS GROUP INC | 1.7M | $127.6M | +58.8% | 1.029% | 0.01% |
| 18 | AMERICAN CENTURY COMPANIES INC | 1.7M | $124.9M | +2.9% | 1.007% | 0.06% |
| 19 | CHARLES SCHWAB INVESTMENT MANAGEMENT INC | 1.6M | $118.9M | +2.7% | 0.958% | 0.02% |
| 20 | FRANKLIN RESOURCES INC | 1.6M | $118.3M | +19.2% | 0.953% | 0.03% |
| 21 | UBS ASSET MANAGEMENT AMERICAS INC | 1.5M | $110.8M | +6.3% | 0.893% | 0.02% |
| 22 | Pictet Asset Management Holding SA | 1.4M | $107.1M | +1.2% | 0.868% | 0.11% |
| 23 | CITADEL ADVISORS LLC | 1.3M | $98.1M | -43.5% | 0.790% | 0.05% |
| 24 | Invesco Ltd. | 1.3M | $95.9M | +0.6% | 0.773% | 0.01% |
| 25 | SUSQUEHANNA INTERNATIONAL GROUP, LLP | 1.2M | $91.8M | +44.1% | 0.740% | 0.01% |
denotes a marquee investor (Buffett, Burry, ARK, Tiger Global, Pershing Square, Baupost and other widely-followed managers). “% of Fund” shows how much of that investor’s total 13F portfolio is invested in IONS — a direct measure of their conviction.
Filings activity in IONS during Q1 2026, grouped by how each filer changed its position.
8 quarters of 13F filings · Δ columns show change vs prior quarter
| Quarter | Inst. Holders | Δ Holders | Ownership % | Δ Ownership | Total 13F Value | Δ Value |
|---|---|---|---|---|---|---|
| Q1 2026 | 479 | 1.0% | 98.10% | 2.74 pp | $11.88B | 2.7% |
| Q4 2025 | 484 | +14% | 100.84% | +16.87 pp | $12.21B | +20% |
| Q3 2025 | 425 | +17% | 83.97% | +36.22 pp | $10.17B | +76% |
| Q2 2025 | 362 | +7.7% | 47.75% | +12.73 pp | $5.78B | +36% |
| Q1 2025 | 336 | 3.2% | 35.02% | 4.65 pp | $4.24B | 12% |
| Q4 2024 | 347 | +2.4% | 39.67% | 4.81 pp | $4.80B | 11% |
| Q3 2024 | 339 | 2.9% | 44.48% | 4.53 pp | $5.39B | 9.2% |
| Q2 2024 | 349 | — | 49.01% | — | $5.93B | — |
Source: SEC 13F institutional filings. Ownership % requires market cap data and will show once linked. Δ columns compare to the immediately prior filed quarter.
Quick answers to the most common questions about buying IONS stock.
Based on Q1 2026 13F filings, institutional ownership of Ionis Pharmaceuticals, Inc. stands at 98.1%, held across 479 reporting institutions.
FMR LLC is the largest reported institutional holder of IONS, with approximately 24,556,637 shares worth $1.84B as of Q1 2026.
Yes — 3 widely-followed marquee investors appear among the top 25 institutional holders of IONS, including TWO SIGMA INVESTMENTS, LP, CITADEL ADVISORS LLC, SUSQUEHANNA INTERNATIONAL GROUP, LLP.
Our composite Smart Money Score for IONS is 47 out of 100 (Neutral). It combines net institutional buying activity, ownership shift, marquee investor presence, and holder-count growth.
76 institutions opened new positions in IONS during Q1 2026, while 81 fully exited. 131 added to existing positions and 269 trimmed.
IONS institutional ownership fell by 2.74 percentage points quarter-over-quarter, with a net change of -5 holders.
The top 10 institutions account for 60.2% of all reported 13F value in IONS, and the top 25 account for 76.2%.
All data is sourced from SEC Form 13F filings, which institutional investment managers with at least $100M in assets are required to file each quarter. We process every 13F filing from EDGAR and recompute the aggregates after each cycle. Insider transactions are sourced from Form 4 filings.
Ionis Pharmaceuticals, Inc. (IONS) Institutional Ownership