[Form 4] IONIS PHARMACEUTICALS INC Insider Trading Activity

Rhea-AI Filing Summary

Ionis Pharmaceuticals (IONS) disclosed insider transactions by EVP, Corp and Development Ops Brian Birchler. On 10/14/2025 and 10/15/2025, he exercised non-qualified stock options at $53.77 for 11,475 and 12,425 shares (codes M) and sold the same amounts at weighted average prices of $72.0339 and $72.2252 (codes S) pursuant to a Rule 10b5-1 trading plan adopted on August 12, 2024. After these trades, he directly owned 56,826 shares.

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

OMB Number:			3235-0287
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hours per response:			0.5

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^*

Birchler Brian

(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, Corp and Development Ops

3. Date of Earliest Transaction (Month/Day/Year)
10/14/2025

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	10/14/2025		M		11,475	A	$53.77	68,301	D
Common Stock	10/14/2025		S		11,475(1)	D	$72.0339(2)	56,826	D
Common Stock	10/15/2025		M		12,425	A	$53.77	69,251	D
Common Stock	10/15/2025		S		12,425(1)	D	$72.2252(3)	56,826	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)	$53.77	10/14/2025		M			11,475	01/02/2020	01/01/2026	Common Stock	11,475	$0.0	12,425	D
Non-Qualified Stock Option (right to buy)	$53.77	10/15/2025		M			12,425	01/02/2021	01/01/2026	Common Stock	12,425	$0.0	0	D

Explanation of Responses:

1. Shares sold pursuant to a Rule 10b5-1 Trading Plan adopted by the reporting person on August 12, 2024.

2. The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $72.00 to $72.115, 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 (2) of this Form 4.

3. The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $72.00 to $72.46, 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) of this Form 4.

	By: Patrick R. O'Neil, attorney-in-fact For: Brian Birchler	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 insider transactions did IONS disclose?

The EVP, Corp and Development Ops, Brian Birchler, exercised options at $53.77 and sold the resulting shares at weighted average prices of $72.0339 and $72.2252 on 10/14/2025 and 10/15/2025.

How many Ionis (IONS) shares were involved?

He exercised and sold 11,475 shares on 10/14/2025 and 12,425 shares on 10/15/2025, matching each day’s option exercise and sale.

Was a Rule 10b5-1 trading plan used by the IONS insider?

Yes. Sales were made pursuant to a Rule 10b5-1 trading plan adopted on August 12, 2024.

What were the weighted average sale prices reported?

Weighted average sale prices were $72.0339 on 10/14/2025 and $72.2252 on 10/15/2025.

How many IONS shares does the insider own after these trades?

Following the reported transactions, he directly owned 56,826 shares.

What were the option grant details tied to these exercises?

Non-qualified stock options with a $53.77 exercise price, originally exercisable from 01/02/2020 and 01/02/2021, expiring 01/01/2026, were exercised.