Capital World Investors reports 11.1% Ionis Pharmaceuticals (IONS) stake

Rhea-AI Filing Summary

Capital World Investors reports beneficial ownership of 17,961,299 shares of Ionis Pharmaceuticals, Inc. common stock, representing 11.1% of the class, based on 161,974,393 shares believed outstanding as of the event date. The firm has sole voting and dispositive power over all reported shares and no shared power. It certifies that the shares were acquired and are held in the ordinary course of business and not for the purpose of changing or influencing control of Ionis.

Insights

Institutional ownership analyst

Capital World Investors discloses a passive 11.1% stake in Ionis.

Capital World Investors, an investment adviser division of Capital Research and Management Company and affiliates, reports beneficial ownership of 17,961,299 Ionis common shares, equal to 11.1% of the 161,974,393 shares believed outstanding. The firm has sole voting and dispositive power over these shares, indicating centralized decision-making for this position.

The certification states the position was acquired and is held in the ordinary course of business and not with the purpose or effect of changing or influencing control of Ionis Pharmaceuticals. This aligns the filing with a passive Schedule 13G, rather than an activist Schedule 13D. Future ownership updates, if any, would be reflected in subsequent beneficial ownership reports.

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Accepted by SEC EDGAR 01/07/2026 - 07:48 PM Learn about SEC filing dates

FAQ

How many Ionis Pharmaceuticals (IONS) shares does Capital World Investors report owning?

Capital World Investors reports beneficial ownership of 17,961,299 shares of Ionis Pharmaceuticals common stock.

What percentage of Ionis Pharmaceuticals common stock is held by Capital World Investors?

Capital World Investors reports holding 11.1% of Ionis Pharmaceuticals' common stock, based on 161,974,393 shares believed to be outstanding.

Is Capital World Investors filing as a passive or activist holder of Ionis (IONS)?

Capital World Investors certifies that the Ionis shares were acquired and are held in the ordinary course of business and not for the purpose of changing or influencing control of the company.

What voting and dispositive power does Capital World Investors have over its Ionis stake?

Capital World Investors reports sole voting power and sole dispositive power over all 17,961,299 Ionis shares, with no shared voting or dispositive power.

What type of reporting person is Capital World Investors in this Ionis filing?

Capital World Investors is classified as an investment adviser (IA) for this beneficial ownership report.

Who signed the Ionis Pharmaceuticals Schedule 13G/A on behalf of Capital World Investors?

The filing was signed by Timothy J. Moon, Vice President and Senior Counsel of Capital Research and Management Company, on 01/05/2026.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 1)

Ionis Pharmaceuticals, Inc.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

462222100

(CUSIP Number)

12/31/2025

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13G

CUSIP No. 462222100

1

Names of Reporting Persons

Capital World Investors

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 17,961,299.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 17,961,299.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

17,961,299.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

11.1 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Ionis Pharmaceuticals, Inc.
(b)	Address of issuer's principal executive offices: 2855 GAZELLE COURT, CARLSBAD, CA 92010
Item 2.
(a)	Name of person filing: Capital World Investors
(b)	Address or principal business office or, if none, residence: 333 SOUTH HOPE STREET, 55TH FLOOR, LOS ANGELES, CALIFORNIA 90071
(c)	Citizenship: N/A
(d)	Title of class of securities: Common Stock
(e)	CUSIP No.: 462222100
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 17,961,299 ** **Capital World Investors ("CWI") is a division of Capital Research and Management Company ("CRMC"), as well as its investment management subsidiaries and affiliates Capital Bank and Trust Company, Capital International, Inc., Capital International Limited, Capital International Sarl, Capital International K.K., Capital Group Private Client Services, Inc., and Capital Group Investment Management Private Limited (together with CRMC, the "investment management entities"). CWI's divisions of each of the investment management entities collectively provide investment management services under the name "Capital World Investors." CWI is deemed to be the beneficial owner of 17,961,299 shares or 11.1% of the 161,974,393 shares believed to be outstanding.
(b)	Percent of class: 11.1 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 17,961,299
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 17,961,299
	(iv) Shared power to dispose or to direct the disposition of: 0
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Capital World Investors

Signature:	Timothy J. Moon
Name/Title:	Vice President and Senior Counsel, Capital Research and Management Company
Date:	01/05/2026