Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2024

Share-Based Payment Arrangement [Abstract]

Stock Awards Granted

The following table summarizes the Company’s stock awards granted under all plans for each of the periods indicated:

	Three Months Ended March 31,
	2024			2023
	Grants	Weighted Average Grant Date Fair Value		Grants	Weighted Average Grant Date Fair Value
Stock options	1,044,658	$	26.50	177,620	$	11.00

Stock-Based Compensation Expense

Total stock-based compensation expense recognized from the Company’s equity incentive plans, 2018 Plan, 2016 ESPP and Parapyre Option Obligation during the periods presented was as follows (in thousands):

	Three Months Ended March 31,
	2024		2023
Research and development (1)	$	6,857	$	777
General and administrative	6,978		932
Total stock-based compensation expense	$	13,835	$	1,709
(1) For the three months ended March 31, 2024, $5.4 million, was recognized as stock compensation expense related to the Parapyre Option Obligation. There were no such expenses for the three months ended March 31, 2023. (2) Of the total $13.8 million and $1.7 million of stock-based compensation expense for the three months ended March 31, 2024 and 2023, respectively, $2.9 million and $0.5 million, respectively, is related to legacy Aeglea employees and directors who had been terminated as of the end of the period.

Assumptions used to Estimate the Fair Value of Stock Options Granted

The following table summarizes the weighted-average Black-Scholes option pricing model assumptions used to estimate the fair value of stock options granted under the Company's equity incentive plans, and the shares purchasable under the 2016 ESPP during the periods presented:

	Three Months Ended March 31,
	2024	2023
Stock Options Granted
Expected term (in years)	6.03	6.02
Expected volatility	105%	99%
Risk-free interest	3.88%	4.06%
Dividend yield	—	—
2016 ESPP
Expected term (in years)	0.50	0.49
Expected volatility	98%	181%
Risk-free interest	5.31	4.99
Dividend yield	—	—