During the six months ended June 30, 2026, the Company issued option grants for 57,800 shares and restricted stock unit ("RSU") grants of 6,208 shares to employees under its 2016 Omnibus Incentive Plan. The share-based awards are accounted for as equity awards, are subject only to service vesting conditions, and vest over a period of 4 years for employees. The Company did not grant any non-employee stock options during the three and six months ended June 30, 2026 under the 2016 Omnibus Incentive Plan.

The fair value of options granted to employees is estimated on the grant date using the Black-Scholes valuation with following assumptions:


	Six Months Ended June 30, 2026	Six Months Ended June 30, 2025
Fair value of share of common stock (1)	$48.31-$64.75	$24.33-$29.18
Expected term in years (2)	6.25	5.50-6.25
Volatility (3)	84.24%-84.46%	83.14%-83.28%
Risk-free interest rate (4)	3.92%-4.28%	4.18%-4.25%
Expected dividend (5)	—%	—%

(1)Fair value of Class A common stock value was closing market price of the Class A common stock on the grant date.

(2)Expected term of share options is based on the average of the vesting period and the contractual term for each grant.

(3)Volatility is calculated based on the historical volatility of ACM in the period equal to the expected term of each grant.

(4)Risk-free interest rate is based on the yields of U.S. Treasury securities with maturities similar to the expected term of the share options in effect at the time of grant.

(5) Expected dividend is assumed to be nil as ACM has no history or expectation of paying a dividend on its Class A common stock.

No options were granted under ACM Shanghai 2023 Option Plan during the three and six months ended June 30, 2026.

The following table summarizes the components of stock-based compensation expense included in the condensed consolidated statements of comprehensive income:


	Three Months Ended June 30,				Six Months Ended June 30,
	2026		2025		2026		2025
Stock-based compensation expense:
Cost of revenue	$	177	$	356	$	525	$	885
Sales and marketing expense	1,330		2,096		2,822		4,253
Research and development expense	1,532		2,580		3,374		5,355
General and administrative expense	3,544		4,738		5,483		9,094
Total stock-based compensation expense	$	6,583	$	9,770	$	12,204	$	19,587