The compensation cost recorded for stock options for the three months ended March 31, 2024 and 2023 was $2.1 million and $1.9 million, respectively.

The compensation cost recorded for stock equivalent units for the three months ended March 31, 2024 and 2023 was $2.5 million and $3.2 million, respectively.

The following table summarizes the transactions of the Company’s stock-based compensation plans for the three months ended March 31, 2024.


	Number of shares			Weighted Average Grant-Date Fair Value
Nonvested at December 31, 2023		652,891		$	75.2
Granted		135,942		$	130.5
Vested		(160,207	)	$	86.6
Forfeited		(7,151	)	$	83.9
Nonvested at March 31, 2024		621,475		$	84.2

For the awards granted with market conditions during the three months ended March 31, 2024, a Monte Carlo model has been used to calculate the grant-date fair value. For all other awards granted in the quarter, a fair market value methodology has been used to calculate the grant-date fair value.

The awards granted with market conditions during the three months ended March 31, 2024, include a performance measure for Innospec's total shareholder return as compared to a peer group of companies. This measure can result in a maximum 130% vesting for the number of stock options granted. The maximum potential vesting has been reflected in the grant-date fair value calculation, but not reflected for the number of awards granted, as shown in the table above. All other awards granted in the quarter have similar vesting conditions to those granted in the previous periods.

As of March 31, 2024, there was $34.6 million of total unrecognized compensation cost related to nonvested share-based compensation arrangements. That cost is expected to be recognized over a weighted-average period of 2.2 years.