Stock-based Compensation Expense (Tables)

9 Months Ended

Sep. 30, 2023

Stock-based Compensation Expense [Abstract]

Weighted-Average Assumptions for Stock Options

Employee Stock Options:

	Nine Months Ended September 30,
	2023			2022
Risk-free interest rate		3.7	%		1.9	%
Dividend yield		0.0	%		0.0	%
Volatility		47.1	%		54.9	%
Expected life	6.3 years			6.3 years

Ionis Board of Director Stock Options:

	Nine Months Ended September 30,
	2023			2022
Risk-free interest rate		3.8	%		2.9	%
Dividend yield		0.0	%		0.0	%
Volatility		53.0	%		56.2	%
Expected life	7.7 years			7.4 years

Weighted-Average Assumptions for ESPP

ESPP:

	Nine Months Ended September 30,
	2023			2022
Risk-free interest rate		5.3	%		1.2	%
Dividend yield		0.0	%		0.0	%
Volatility		36.0	%		50.1	%
Expected life	6 months			6 months

Stock-Based Compensation Expense

The following table summarizes stock-based compensation expense for the three and nine months ended September 30, 2023 and 2022 (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Cost of sales	$	118	$	163	$	355	$	376
Research, development and patent expense		18,727		17,733		57,543		55,315
Selling, general and administrative expense		7,119		5,941		21,575		18,884
Total stock-based compensation expense	$	25,964	$	23,837	$	79,473	$	74,575