Comparable stake leader
Capital World Investors
SEC ownership of IONIS PHARMACEUTICALS INC
Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0000874015.
Disclosed value leader
FMR LLC
Comparable rows
5/50
Latest evidence
31 Aug 2026
- Public ticker
- IONS on Nasdaq
- Parsed ownership sources
-
13F, 13D/G, and 3/4/5
Source: Parsed SEC ownership filingsUse: Compare filing families carefully
- Largest SEC-reported holder
-
Capital World Investors
Ranking: Comparable ownership first, then disclosed value
- Comparable ownership rows
-
5 of 50
Meaning: Rows with safely comparable ownership %
- Latest 13D/G holder
-
Capital World Investors
Source: Latest parsed Schedule 13D/G stake
- Latest parsed ownership date
-
31 Aug 2026
Freshness: Most recent filing date in this holder set
- Issuer CIK
- 0000874015
- Issuer location
- Carlsbad, CA
Ownership snapshot
CIK-linked ownership evidence from parsed SEC filings.
3 signals
Issuer
Names, identifiers, and filing context for this profile.
2 identity fields
Ownership snapshot
Top shareholders of IONIS PHARMACEUTICALS INC (13F + 13D/G + 3/4/5)
Grouped by holder across the latest SEC ownership disclosures. Start with comparable ownership when available, then verify the linked 13F, 13D/G, or 3/4/5 evidence.
Comparable stake leader
Capital World Investors
Disclosed value leader
FMR LLC
Comparable rows
5/50
Latest evidence
31 Aug 2026
13F
13D/G
3/4/5
Lead comparable stake: 13%
45 rows are not safely comparable across share classes.
13D/G row: Capital World Investors
Showing 1-8 of 50 holder rows.
Quick read
Capital World Investors leads the comparable SEC ownership view at 13%.
5 of 50 rows have a safely comparable ownership percentage. Use this as a filing-backed starting point, then open the detailed table for source links, reporting role, position value, share count, and filing date.
Open SEC evidence
Opens Capital World Investors's linked filing trail.
Comparable ownership
Top 5
Capital World Investors
13%
BlackRock, Inc.
5.7%
VANGUARD CAPITAL MANAGEMENT LLC
5%
WELLINGTON MANAGEMENT GROUP LLP
4.3%
T. Rowe Price Investment Manageme...
3.7%
Ownership % is shown only when SEC disclosures are safely comparable across share classes.
Detailed SEC evidence table Showing 1-8 of 50 holder rows
| Holder | Evidence | Ownership % | Position | 12M Net Δ | As of |
|---|---|---|---|---|---|
| Capital World Investors |
13F
13D/G
Company
|
13%
Reported 13D/G
· 31 Mar 2026
|
$1,718,152,930
21,669,226 shares
|
— | 30 Jun 2026 |
| BlackRock, Inc. |
13F
13D/G
Company
|
5.7%
Reported 13D/G
· 31 Mar 2025
|
$848,772,532
10,704,660 shares
|
— | 30 Jun 2026 |
| VANGUARD CAPITAL MANAGEMENT LLC |
13D/G
13F
Vanguard Capital Management · Company
|
5%
Reported 13D/G
· 31 Mar 2026
|
$626,605,926
8,344,732 shares
|
$0 | 31 Mar 2026 |
| WELLINGTON MANAGEMENT GROUP LLP |
13F
13D/G
Company
|
4.3%
Reported 13D/G
· 30 Jun 2025
|
$606,680,694
7,651,415 shares
|
— | 30 Jun 2026 |
| T. Rowe Price Investment Management, Inc. |
13D/G
13F
Company
|
3.7%
Reported 13D/G
· 31 Mar 2026
|
$462,974,060
6,159,027 shares
|
-$221,675,729 | 31 Mar 2026 |
| FMR LLC |
13F
Company
|
—
denominator unverified
|
$1,953,067,764
24,631,956 shares
|
— | 30 Jun 2026 |
| VANGUARD PORTFOLIO MANAGEMENT LLC |
13F
Company
|
—
denominator unverified
|
$623,182,054
7,859,529 shares
|
— | 30 Jun 2026 |
| TWO SIGMA INVESTMENTS, LP |
13F
Company
|
—
denominator unverified
|
$495,748,197
6,252,342 shares
|
— | 30 Jun 2026 |
How to read this table
Rows are grouped by holder and ranked first by SEC-reported ownership % when it is safely comparable, then by disclosed holdings value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.
Forms 3/4/5 flow
Insider trading overview
Net insider flow leans to selling over the last 12 months. Net value: -$112,481,105.
Buys
$1,206,900
Insiders: 1
Sells
$113,688,005
Insiders: 18
Net
-$112,481,105
Shares: -1,447,177
Window
Last 12 months
4 rolling buckets
Buy value
Sell value
Shares: 25,000
Shares: 1,472,177
| Window (months) | Buy shares | Sell shares | Buy value | Sell value | Net value |
|---|---|---|---|---|---|
| 0-3 | 5,000 | 1,410 | $148,200 | $61,389 | +$86,811 |
| 3-6 | 20,000 | 250,316 | $1,058,700 | $19,678,332 | -$18,619,632 |
| 6-9 | 0 | 766,896 | $0 | $57,837,778 | -$57,837,778 |
| 9-12 | 0 | 453,555 | $0 | $36,110,506 | -$36,110,506 |
Reporting owners
Insider holders from Forms 3/4/5
Showing 1-20 of 25 reporting-owner rows connected to IONIS PHARMACEUTICALS INC. Open a relationship link for the CIK-to-CIK filing trail.
Rows
25
Largest Forms 3/4/5 holder
Brett P. Monia
Net 12M change
-$112.48M
Full value: -$112,481,104 · USD · 12-month changeLatest report
10 Nov 2026
| Name | Relationship | Holdings Value | Past Year Net Change | Change % | Valuation | Report Date |
|---|---|---|---|---|---|---|
| Brett P. Monia | Chief Executive Officer, Director | $48,195,142 | -$30,324,115 | -39% | Mixed | 31 Aug 2026 |
| Spencer R. Berthelsen | Director | $12,954,057 | -$1,193,280 | -8.4% | Mixed | 15 Jul 2026 |
| HOUGEN ELIZABETH L | EVP, Finance & CFO | $11,680,853 | -$17,867,371 | -60% | Mixed | 16 Mar 2026 |
| Brian Birchler | EVP, Corp and Development Ops | $11,648,257 | -$1,222,997 | -9.5% | Mixed | 31 Aug 2026 |
| Eugene Schneider | EVP, Chf Clinical Develop Ofcr | $10,398,607 | -$3,738,450 | -26% | Mixed | 26 Jun 2026 |
| Patrick R. O'Neil | EVP CLO & General Counsel | $8,790,747 | -$2,222,381 | -20% | Mixed | 31 Aug 2026 |
| Richard S. Geary | EVP, Chief Development Officer | $8,613,598 | Mixed | 05 Nov 2025 | ||
| C. Frank Bennett | EVP, Chief Scientific Officer | $8,102,000 | -$9,649,055 | -54% | Mixed | 31 Aug 2026 |
| Onaiza Cadoret-Manier | EVP,Chf GL Pdt Str & Oper Ofc | $7,945,126 | Mixed | 02 Feb 2024 | ||
| Joseph Baroldi | EVP, Chief Business Officer | $7,762,433 | -$2,568,005 | -25% | Mixed | 26 Jun 2026 |
| Eric Swayze | EVP Research | $5,110,912 | -$5,237,867 | -51% | Mixed | 15 Oct 2026 |
| Joan E. Herman | Director | $4,068,052 | -$3,173,830 | -44% | Mixed | 15 Jul 2026 |
| Joseph H. Wender | Director | $4,044,699 | -$2,262,848 | -36% | Mixed | 01 Dec 2025 |
| B. Lynne Parshall | Director | $3,951,947 | -$794,955 | -17% | Filing P/S | 15 Apr 2026 |
| Kyle Jenne | EVP, Chf GL Pdt Str Ofcr | $3,581,402 | -$3,334,288 | -48% | Mixed | 15 Apr 2026 |
| Shannon L. Devers | EVP, Chief Human Resources Ofc | $3,562,356 | -$8,190,048 | -70% | Mixed | 15 Oct 2026 |
| Frederick T. Muto | Director | $3,438,793 | Mixed | 15 Jul 2022 | ||
| Michael R. Hayden | Director | $3,224,685 | +$1,206,900 | +60% | Mixed | 10 Nov 2026 |
| Joseph Loscalzo | Director | $2,745,915 | -$5,884,059 | -68% | Filing P/S | 01 Jul 2026 |
| Holly B. Kordasiewicz | EVP, Chief Development Officer | $1,862,692 | -$4,810,252 | -72% | Filing P/S | 07 Jul 2026 |
Recent insider transactions for IONIS PHARMACEUTICALS INC
Showing up to 300 recent insider transactions from the last 12 months.
| Insider | Symbol | Class | Transaction | % | SEC-reported value | SEC-reported price | Shares | Shares owned | Date | Ownership |
|---|---|---|---|---|---|---|---|---|---|---|
| Michael R. Hayden | IONS | Common Stock | Purchase | 22.7% | $148,200 | $29.64 | 5,000 | 27,000 | 10 Nov 2026 | by Spouse |
| Shannon L. Devers | IONS | Common Stock | Sale | -7.08% | -$59,082 | $43.54 | -1,357 | 17,811 | 16 Oct 2026 | Direct |
| Eric Swayze | IONS | Common Stock | Sale | -12% | -$2,308 | $43.54 | -53 | 390 | 16 Oct 2026 | by Son |
| Shannon L. Devers | IONS | Common Stock | Options Exercise | 17.2% | 2,820 | 19,168 | 15 Oct 2026 | Direct | ||
| Shannon L. Devers | IONS | Restricted Stock Unit | Options Exercise | -5.35% | -2,820 | 49,884 | 15 Oct 2026 | Direct | ||
| Eric Swayze | IONS | Common Stock | Options Exercise | 39.3% | 125 | 443 | 15 Oct 2026 | by Son | ||
| Eric Swayze | IONS | Restricted Stock Unit | Options Exercise | -20.5% | -125 | 486 | 15 Oct 2026 | by Son | ||
| C. Frank Bennett | IONS | Common Stock | Other | 0.18% | 110 | 60,128 | 31 Aug 2026 | Direct | ||
| Patrick R. O'Neil | IONS | Common Stock | Other | 0.11% | 63 | 59,205 | 31 Aug 2026 | Direct | ||
| Brett P. Monia | IONS | Common Stock | Other | 0.04% | 98 | 242,760 | 31 Aug 2026 | Direct | ||
| Brian Birchler | IONS | Common Stock | Other | 0.06% | 58 | 102,883 | 31 Aug 2026 | Direct | ||
| Michael R. Hayden | IONS | Common Stock | Purchase | 26.3% | $258,000 | $51.60 | 5,000 | 24,000 | 31 Jul 2026 | by Spouse |
| Michael R. Hayden | IONS | Common Stock | Purchase | 375% | $800,700 | $53.38 | 15,000 | 19,000 | 30 Jul 2026 | by Spouse |
| Peter N. Reikes | IONS | Restricted Stock Unit | Award | 3,399 | 3,399 | 15 Jul 2026 | Direct | |||
| Ludwig Hantson | IONS | Restricted Stock Unit | Award | 3,399 | 3,399 | 15 Jul 2026 | Direct | |||
| Joan E. Herman | IONS | Common Stock | Options Exercise | 11.3% | 5,220 | 51,306 | 15 Jul 2026 | Direct | ||
| Joan E. Herman | IONS | Restricted Stock Unit | Options Exercise | -69.4% | -5,220 | 2,301 | 15 Jul 2026 | Direct | ||
| Spencer R. Berthelsen | IONS | Common Stock | Options Exercise | 3.35% | 5,220 | 161,233 | 15 Jul 2026 | Direct | ||
| Spencer R. Berthelsen | IONS | Restricted Stock Unit | Options Exercise | -69.4% | -5,220 | 2,301 | 15 Jul 2026 | Direct | ||
| C. Frank Bennett | IONS | Common Stock | Sale | -100% | -$1,281,930 | $85.46 | -15,000 | 0 | 07 Jul 2026 | by Trust |
| C. Frank Bennett | IONS | Common Stock | Other | 15,000 | 15,000 | 07 Jul 2026 | by Trust | |||
| C. Frank Bennett | IONS | Common Stock | Sale | -6.87% | -$462,693 | $83.58 | -5,536 | 75,018 | 07 Jul 2026 | Direct |
| C. Frank Bennett | IONS | Restricted Stock Unit | Other | -55.3% | -15,000 | 12,109 | 07 Jul 2026 | Direct | ||
| Allene M. Diaz | IONS | Common Stock | Sale | -72.6% | -$863,637 | $85.42 | -10,111 | 3,811 | 07 Jul 2026 | Direct |
| Allene M. Diaz | IONS | Common Stock | Options Exercise | 265.3% | 10,111 | 13,922 | 07 Jul 2026 | Direct | ||
| Allene M. Diaz | IONS | Non-Qualified Stock Option (right to buy) | Options Exercise | -100% | -10,111 | 0 | 07 Jul 2026 | Direct | ||
| Holly B. Kordasiewicz | IONS | Common Stock | Sale | -1.61% | -$30,517 | $84.30 | -362 | 22,096 | 07 Jul 2026 | Direct |
| Michael J. Yang | IONS | Restricted Stock Unit | Award | 32.2% | 2,301 | 9,451 | 01 Jul 2026 | Direct | ||
| Michael J. Yang | IONS | Non-Qualified Stock Option (right to buy) | Award | 5,369 | 5,369 | 01 Jul 2026 | Direct | |||
| Joseph Loscalzo | IONS | Restricted Stock Unit | Award | 44.1% | 2,301 | 7,521 | 01 Jul 2026 | Direct | ||
| Joseph Loscalzo | IONS | Non-Qualified Stock Option (right to buy) | Award | 5,369 | 5,369 | 01 Jul 2026 | Direct | |||
| Joan E. Herman | IONS | Restricted Stock Unit | Award | 44.1% | 2,301 | 7,521 | 01 Jul 2026 | Direct | ||
| Joan E. Herman | IONS | Non-Qualified Stock Option (right to buy) | Award | 5,369 | 5,369 | 01 Jul 2026 | Direct | |||
| Joseph Klein III | IONS | Common Stock | Sale | -51.1% | -$910,416 | $79.04 | -11,518 | 11,014 | 01 Jul 2026 | Direct |
| Joseph Klein III | IONS | Common Stock | Options Exercise | 104.6% | 11,518 | 22,532 | 01 Jul 2026 | Direct | ||
| Joseph Klein III | IONS | Restricted Stock Unit | Award | 16.5% | 2,301 | 16,277 | 01 Jul 2026 | Direct | ||
| Joseph Klein III | IONS | Non-Qualified Stock Option (right to buy) | Award | 5,369 | 5,369 | 01 Jul 2026 | Direct | |||
| Joseph Klein III | IONS | Non-Qualified Stock Option (right to buy) | Options Exercise | -100% | -11,518 | 0 | 01 Jul 2026 | Direct | ||
| Michael R. Hayden | IONS | Restricted Stock Unit | Award | 23.2% | 2,301 | 12,198 | 01 Jul 2026 | Direct | ||
| Michael R. Hayden | IONS | Non-Qualified Stock Option (right to buy) | Award | 5,369 | 5,369 | 01 Jul 2026 | Direct | |||
| Allene M. Diaz | IONS | Restricted Stock Unit | Award | 44.1% | 2,301 | 7,521 | 01 Jul 2026 | Direct | ||
| Allene M. Diaz | IONS | Non-Qualified Stock Option (right to buy) | Award | 5,369 | 5,369 | 01 Jul 2026 | Direct | |||
| Spencer R. Berthelsen | IONS | Restricted Stock Unit | Award | 44.1% | 2,301 | 7,521 | 01 Jul 2026 | Direct | ||
| Spencer R. Berthelsen | IONS | Non-Qualified Stock Option (right to buy) | Award | 5,369 | 5,369 | 01 Jul 2026 | Direct | |||
| Joseph Baroldi | IONS | Common Stock | Sale | -54.7% | -$451,699 | $80.16 | -5,635 | 4,669 | 26 Jun 2026 | by Spouse |
| Joseph Baroldi | IONS | Common Stock | Options Exercise | 120.7% | 5,635 | 10,304 | 26 Jun 2026 | by Spouse | ||
| Joseph Baroldi | IONS | Non-Qualified Stock Option (right to buy) | Options Exercise | -100% | -5,635 | 0 | 26 Jun 2026 | by Spouse | ||
| Patrick R. O'Neil | IONS | Common Stock | Sale | -4.76% | -$245,520 | $80.00 | -3,069 | 61,470 | 26 Jun 2026 | Direct |
| Eugene Schneider | IONS | Common Stock | Sale | -25.2% | -$2,107,196 | $81.05 | -26,000 | 77,114 | 26 Jun 2026 | Direct |
| Eugene Schneider | IONS | Common Stock | Options Exercise | 33.7% | 26,000 | 103,114 | 26 Jun 2026 | Direct |
* marks a reported price that did not pass the local price check.