[Form 4] IONIS PHARMACEUTICALS INC Insider Trading Activity

Rhea-AI Filing Summary

Ionis Pharmaceuticals (IONS) — Form 4: EVP and Chief Human Resources Officer Shannon L. Devers exercised options for 6,000 shares at $48.51 on 10/15/2025, then sold 6,000 shares the same day at a weighted average price of $72.9423 pursuant to a Rule 10b5-1 trading plan adopted on September 3, 2024. Also on 10/15/2025, 2,820 shares were acquired upon RSU vesting at no cost, and on 10/16/2025, 1,263 shares were sold at $73.6213 to cover tax withholding.

Following these transactions, Devers directly owned 17,494 shares of common stock. RSUs vest in four equal annual installments; each RSU represents a right to one share or its cash equivalent. The stock option exercised was originally granted on 04/05/2021 and expires on 04/04/2027.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

X

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Devers Shannon L.

(Last) (First) (Middle)

2855 GAZELLE COURT

(Street)

CARLSBAD CA 92010

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
IONIS PHARMACEUTICALS INC [ IONS ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	EVP, Chief Human Resources Ofc

3. Date of Earliest Transaction (Month/Day/Year)
10/15/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	10/15/2025		M		6,000	A	$48.51	21,937	D
Common Stock	10/15/2025		S		6,000(1)	D	$72.9423(2)	15,937	D
Common Stock	10/15/2025		M(3)		2,820(3)	A	$0.0	18,757	D
Common Stock	10/16/2025		S(4)		1,263(4)	D	$73.6213	17,494	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Non-Qualified Stock Option (right to buy)	$48.51	10/15/2025		M			6,000	04/05/2021	04/04/2027	Common Stock	6,000	$0.0	0	D
Restricted Stock Unit	$0.0(5)	10/15/2025		M			2,820	10/15/2025(6)	(6)	Common Stock	2,820	$0.0	60,406	D

Explanation of Responses:

1. Shares sold pursuant to a Rule 10b5-1 Trading Plan adopted by the reporting person on September 3, 2024.

2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $72.775 to $73.04 inclusive. The reporting person undertakes to provide to Ionis Pharmaceuticals, Inc. any security holder of Ionis Pharmaceuticals, Inc. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (3) on this Form 4.

3. Acquired pursuant to vesting and release of shares in accordance with a Restricted Stock Unit award.

4. The sale was made pursuant to an automatic sale to cover the required tax withholding obligations pursuant to the 2011 Equity Incentive Plan Restricted Stock Unit Agreement and Grant Notice.

5. Each Restricted Stock Unit represents a contingent right to receive one share of Ionis common stock, or its equivalent cash value.

6. Restricted Stock Units vest in four equal annual installments. Upon vesting, the restricted stock units will be paid out in whole shares of Ionis common stock or cash as may be determined by the Company.

	By: Patrick R. O'Neil, attorney-in-fact For: Shannon L. Devers	10/16/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What transactions did IONS executive Shannon L. Devers report?

On 10/15/2025, an option exercise for 6,000 shares at $48.51 and a sale of 6,000 shares at $72.9423; on 10/16/2025, a sale of 1,263 shares at $73.6213 to cover taxes.

Were any sales under a Rule 10b5-1 plan for IONS?

Yes. The 6,000-share sale on 10/15/2025 was made under a Rule 10b5-1 plan adopted on September 3, 2024.

How many IONS shares does the reporting person hold after the transactions?

Devers directly owned 17,494 shares of Ionis common stock after the reported transactions.

What RSU activity was reported for IONS?

On 10/15/2025, 2,820 shares were acquired upon RSU vesting at no cost. RSUs vest in four equal annual installments.

What option grant was exercised in the Form 4?

A non-qualified stock option granted on 04/05/2021 with a $48.51 exercise price and 04/04/2027 expiration was exercised for 6,000 shares.

Why were 1,263 IONS shares sold on 10/16/2025?

The 1,263 shares were sold at $73.6213 as an automatic sale to cover tax withholding related to the RSU vesting.