During the six months ended June 30, 2024 and 2023, the Company granted options to purchase an aggregate of 0 and 233,466 shares of its common stock that are subject to time-based vesting conditions, respectively.

The Company valued these stock options using the Black-Scholes Merton option pricing model. The assumptions used to compute the grant date fair values of the stock options granted during the six months ended June 30, 2024 and 2023 are set forth in the table below:

The assumptions used in calculating the fair values of purchase rights granted under the ESPP during the six months ended June 30, 2024 and 2023 are set forth in the table below:


	Six Months Ended June 30,
	2024	2023
Expected term (in years)	0.5 - 2.0	0.5 - 2.0
Expected volatility	105% - 115%	71% - 101%
Risk-free interest rate	4.7% - 5.2%	0.1% - 4.8%

The Company’s stock-based compensation expense by type of award and by operating expense grouping are presented below:


	Three Months Ended June 30,					Six Months Ended June 30,
	2024			2023		2024			2023
Stock-based compensation expense by type of award:
Restricted stock units	$	1,744		$	1,224	$	2,574		$	3,392
Performance-based stock units		(352	)		142		(352	)		470
Stock options		506			1,081		1,128			2,052
Employee stock purchase plan		241			250		397			700
Total stock-based compensation expense	$	2,139		$	2,697	$	3,747		$	6,614

Stock-based compensation expense by operating expense grouping:
Cost of revenue	$	—		$	17	$	(1	)	$	37
Sales and marketing		306			529		482			705
Research and development		96			1,127		628			2,669
General and administrative		1,737			1,024		2,638			3,203
Total stock-based compensation expense	$	2,139		$	2,697	$	3,747		$	6,614

Stock-based compensation capitalized for internal-use software was $94 and $80 for the three months ended June 30, 2024 and 2023, respectively. Stock-based compensation capitalized for internal-use software was $212 and $214 for the six months ended June 30, 2024 and 2023, respectively.

In connection with the Steel Holdings Consulting Agreement (as defined and further described in Note 12), on January 11, 2023, the Compensation Committee of the Board (the “Compensation Committee”) approved a grant of 118,460 performance stock units (the “Steel Holdings Consulting PSUs”) that were to vest upon the achievement of certain performance milestones. During the year ended December 31, 2023, certain performance milestones were achieved resulting in the vesting of 19,743 shares of the Steel Holdings Consulting PSUs on April 22, 2023 and 39,486 shares on November 15, 2023.

In January 2024, the Company entered into an amended and restated independent contractor services agreement with Steel Holdings, LLC (the “Amended Consulting Agreement”), which supersedes and replaces the Steel Holdings Consulting Agreement. Under the Amended Consulting Agreement, all equity grants that were made, other than vested Steel Holdings PSUs but including unvested Steel Holdings PSUs, or contemplated under the Steel Holdings Consulting Agreement were terminated as of the effective date of the Amended Consulting Agreement and no further performance stock units will be issued under the Amended Consulting Agreement.

On March 16, 2023, the Compensation Committee approved a grant of 170,402 target performance stock units to be granted to the Company’s named executive officers (the “2023 Senior Executive PSUs”). The awards had a grant date of March 31, 2023 and were to vest based on the achievement of revenue and non-GAAP net income targets (each equally weighted) for 2023, which achievement shall then be modified (up to a 20% increase or decrease) based on the Company’s relative total stockholder return over a three-year performance period (the “TSR Modifier”), as compared with the S&P Software and Services Select Industry Index. Based on the Company’s performance, the Company’s named executive officers were to earn from 0% to 200% of the target number of shares of the 2023 Senior Executive PSUs. The 2023 Senior Executive PSUs, to the extent earned, were to vest on the date the Board certifies the TSR Modifier for the three-year performance period ending December 31, 2025 and the number of 2023 Senior Executive PSUs that were to vest as of such certification, all of which was to occur within 90 days of the end of the performance period ending December 31, 2025. Compensation costs recognized on the 2023 Senior Executive PSUs were to be adjusted, as applicable, for performance above or below the target specified in the award. On April 8, 2024, the Compensation Committee determined that, as of December 31, 2023, the revenue and non-GAAP net income targets were not achieved and the 2023 Senior Executive PSUs were forfeited.

On April 8, 2024, the Compensation Committee approved grants of 200,000 and 48,000 target performance stock units to be granted to the Company’s named executive officers, Ryan Steelberg and Michael Zemetra, respectively (the “2024 Senior Executive PSUs”). The awards had a grant date of April 8, 2024 and vest based on the achievement of revenue and non-GAAP net income targets (each equally weighted) for 2024, which achievement shall then be modified (up to a 20% increase or decrease) based on the Company’s relative total stockholder return over a three-year performance period (the “TSR Modifier”), as compared with the S&P Software and Services Select Industry Index. Based on the Company’s performance, the Company’s named executive officers may earn from 0% to 200% of the target number of shares of the 2024 Senior Executive PSUs. The 2024 Senior Executive PSUs, to the extent earned, vest on the date the Board certifies the TSR Modifier for the three-year performance period ending December 31, 2026 and the number of 2024 Senior Executive PSUs that vest as of such certification, all of which shall occur within 90 days of the end of the performance period ending December 31, 2026. Compensation costs recognized on the 2024 Senior Executive PSUs shall be adjusted, as applicable, for performance above or below the target specified in the award.

The Company’s performance stock unit activity for the six months ended June 30, 2024 was as follows:


				Weighted
				Average Grant
	Shares			Date Fair Value
Unvested at December 31, 2023		229,633		$	5.86
Granted		248,000		$	6.97
Forfeited		(229,633	)	$	5.86
Unvested at June 30, 2024		248,000		$	6.97

The Company’s restricted stock unit activity for the six months ended June 30, 2024 was as follows:


				Weighted
				Average Grant
	Shares			Date Fair Value
Unvested at December 31, 2023		1,949,514		$	5.40
Granted		647,365		$	5.82
Forfeited		(318,983	)	$	6.58
Vested		(464,553	)	$	6.37
Unvested at June 30, 2024		1,813,343		$	5.05

As of June 30, 2024, total unrecognized compensation cost related to restricted stock units was $6,963, which is expected to be recognized over a weighted average period of 2.0 years.

The activity during the six months ended June 30, 2024 related to stock options that are subject to performance-based vesting conditions tied to the achievement of stock price goals by the Company was as follows:


				Weighted-Average
							Remaining	Aggregate
					Exercise		Contractual	Intrinsic
	Options				Price		Term	Value
Unvested at December 31, 2023		3,671,310			$	11.29
Expired		(40,479	)		$	5.72
Outstanding at June 30, 2024		3,630,831			$	11.35	6.0 years	$	—
Exercisable at June 30, 2024		3,630,831			$	11.35	6.0 years	$	—

The aggregate intrinsic value of the options exercised during the six months ended June 30, 2024 and 2023 was $0 and $5, respectively. No performance-based stock options were granted during the six months ended June 30, 2024 and 2023 and no performance-based stock options vested during the six months ended June 30, 2024 and 2023.

The activity during the six months ended June 30, 2024 related to all other stock options was as follows:


				Weighted-Average
							Remaining	Aggregate
					Exercise		Contractual	Intrinsic
	Options				Price		Term	Value
Outstanding at December 31, 2023		5,506,374			$	13.81
Exercised		(23,521	)		$	2.81
Forfeited		(208,250	)		$	10.48
Expired		(214,780	)		$	13.42
Outstanding at June 30, 2024		5,059,823			$	14.01	3.9 years	$	56
Exercisable at June 30, 2024		4,723,248			$	14.08	3.6 years	$	56

No stock options were granted during the six months ended June 30, 2024. The weighted average grant date fair value of stock options granted during the six months ended June 30, 2023 was $4.19 per share. The aggregate intrinsic value of the stock options exercised during the six months ended June 30, 2024 and 2023 was $37 and $10, respectively. The total grant date fair value of stock options vested during the six months ended June 30, 2024 and 2023 was $2,004 and $3,202, respectively. At June 30, 2024, total unrecognized compensation expense related to stock options was $3,028 and is expected to be recognized over a weighted average period of 1.9 years.

The aggregate intrinsic values in the tables above represent the difference between the fair market value of the Company’s common stock and the average option exercise price of in-the-money options, multiplied by the number of such stock options.

As of June 30, 2024 and December 31, 2023, employee payroll deductions accrued under the ESPP totaled $276 and $357, respectively. During the six months ended June 30, 2024, a total of 119,954 shares of common stock were purchased under the ESPP.