Ionis Pharmaceuticals Inc (IONS) Institutional Ownership

Institutions by Trading Activity

Ownership Statistics

151,681,657Shares Outstanding

3,082,805Shares held by institutions

$250,817,015Value of institutional holdings

106.57%Institutional ownership %

0.98%Shares Changed QoQ

471No. of institutional investors

Shares Owned by Institutions

Shares Purchased/Sold by Institutions

Ownership Summary

The institutional landscape for Ionis Pharmaceuticals Inc (NASDAQ:IONS) includes 471 filers as of the latest reporting cycle ending December 2025.

The percentage of Ionis Pharmaceuticals owned by institutions changed from 116.1% in September 2025 to 106.6% in December 2025, marking a slight down trend.
Quarterly data indicates a 0.98% shift in institutional share volume, and the annual owner count reflects an increase of 35.73%.
Of these 471 institutional investors, 263 increased their holdings in Ionis Pharmaceuticals, while 140 of them reduced positions, and 68 investors maintained their exposure.
The total number of shares held by institutions in Ionis Pharmaceuticals increased to 161.64Mn as of December 2025, a net change of up by 1.56Mn shares quarter on quarter, and up 1.48Mn shares year over year.
As of December 31, 2025, FMR LLC held Ionis Pharmaceuticals's largest shareholding position with over 24.07Mn shares, representing 15.87% of total outstanding shares.
Among the most significant buyers of Ionis Pharmaceuticals during December 2025 were Capital World Investors (5.24Mn), JPMORGAN CHASE & CO (1.76Mn), FRANKLIN RESOURCES INC (1.31Mn), BAKER BROS. ADVISORS LP (1.23Mn), TWO SIGMA INVESTMENTS, LP (1.08Mn).
Leading sellers of Ionis Pharmaceuticals stock in December 2025 included T. Rowe Price Investment Management, Inc. (7.37Mn), Deep Track Capital, LP (2.11Mn), Bellevue Group AG (1.44Mn), ADAGE CAPITAL PARTNERS GP, L.L.C. (1.18Mn), BANK OF MONTREAL /CAN/ (711.04K).
The top 10 institutional holders of Ionis Pharmaceuticals for the quarter ending December 2025 included FMR LLC (24.07Mn), Capital World Investors (17.96Mn), VANGUARD GROUP INC (16.44Mn), BlackRock, Inc. (10.65Mn), WELLINGTON MANAGEMENT GROUP LLP (6.26Mn), T. Rowe Price Investment Management, Inc. (5.79Mn), Bellevue Group AG (4.80Mn), STATE STREET CORP (3.97Mn), GEODE CAPITAL MANAGEMENT, LLC (3.15Mn), TWO SIGMA ADVISERS, LP (3.05Mn).

471 Institutional Holders

3,082,805 Total Shares Held

Rows:

Download Data

Owner Name	Date	Shares Held	Change (QoQ)	Change (%)	Value (USD)
FMR LLC	31 Dec, 2025	24,072,101	383,063	1.62%	$1,904,343,910.00
Capital World Investors	31 Dec, 2025	17,961,299	5,238,571	41.17%	$1,420,918,364.00
VANGUARD GROUP INC	31 Dec, 2025	16,440,459	-41,271	-0.25%	$1,300,604,712.00
BlackRock, Inc.	31 Dec, 2025	10,647,863	199,923	1.91%	$842,352,443.00
WELLINGTON MANAGEMENT GROUP LLP	31 Dec, 2025	6,260,325	-328,486	-4.99%	$495,254,312.00
T. Rowe Price Investment Management, Inc.	31 Dec, 2025	5,789,863	-7,367,066	-55.99%	$458,037.00
Bellevue Group AG	31 Dec, 2025	4,802,199	-1,442,252	-23.10%	$379,901,963.00
STATE STREET CORP	31 Dec, 2025	3,974,865	-413,786	-9.43%	$314,451,570.00
GEODE CAPITAL MANAGEMENT, LLC	31 Dec, 2025	3,148,849	82,560	2.69%	$249,157,703.00
TWO SIGMA ADVISERS, LP	31 Dec, 2025	3,052,111	979,000	47.22%	$241,452,501.00
TWO SIGMA INVESTMENTS, LP	31 Dec, 2025	2,658,646	1,082,703	68.70%	$210,325,485.00
Tweedy, Browne Co LLC	31 Dec, 2025	2,464,930	-436,286	-15.04%	$195,000,612.00
JPMORGAN CHASE & CO	31 Dec, 2025	2,304,792	1,760,324	323.31%	$182,332,112.00
CITADEL ADVISORS LLC	31 Dec, 2025	2,134,636	-267,429	-11.13%	$168,871,054.00
DEERFIELD MANAGEMENT COMPANY, L.P.	31 Dec, 2025	1,979,669	0	0.00%	$156,611,615.00
BAKER BROS. ADVISORS LP	31 Dec, 2025	1,791,841	1,225,043	216.13%	$141,752,542.00
Deep Track Capital, LP	31 Dec, 2025	1,700,000	-2,108,144	-55.36%	$134,487,000.00
AMERICAN CENTURY COMPANIES INC	31 Dec, 2025	1,617,106	244,881	17.85%	$127,929,439.00
CHARLES SCHWAB INVESTMENT MANAGEMENT INC	31 Dec, 2025	1,541,841	21,890	1.44%	$121,975,042.00
SUMMIT PARTNERS PUBLIC ASSET MANAGEMENT, LLC	31 Dec, 2025	1,462,706	712,706	95.03%	$115,714,672.00

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