*        Amounts include stock-based compensation expense as follows (in thousands):

		(Unaudited)
		Three Months Ended September 30,								Nine Months Ended September 30,
		2021				2020				2021				2020
Cost of revenue – maintenance and other services		$	1,411			$	684			$	3,791			$	1,602
Research and development			3,894				2,428				11,223				5,686
Sales and marketing			3,673				1,949				10,800				3,949
General and administrative			1,955				1,173				5,415				2,702
Total stock-based compensation expense		$	10,933			$	6,234			$	31,229			$	13,939

ALTAIR ENGINEERING INC. AND SUBSIDIARIES