Stockholder's Equity (Deficit) (Tables)

9 Months Ended

Sep. 30, 2020

Summary of Issued and Cancelled Shares of Common Stock

During the three and nine months ended September 30, 2020 and September 30, 2019, the Company issued and cancelled the following shares of common stock:

	Three Months Ended September 30,									Nine Months Ended September 30,
	2020					2019				2020					2019
	Shares			Average Price per Share		Shares		Average Price per Share		Shares			Average Price per Share		Shares		Average Price per Share
Common stock issued    in connection with initial public    offering		11,500,000		$	15.00		—	$	—		11,500,000		$	15.00		—	$	—
Acquisitions		—			—		25,408		26.90		791,139			31.60		150,439		22.41
Redemption of series A-1 preferred stock		1,786,739			15.00		—		—		1,786,739			15.00		—		—
Exercise of warrant options		2,534,239			0.01		—		—		2,534,239			0.01		—		—
Exercise of options		16,850			8.92		7,150		6.03		20,350			9.27		22,675		18.01
Restricted shares, net		8,333			24.00		—		—		8,333			24.00		—		—
Cancellation of shares		(117,785	)		17.15		—		—		(117,785	)		17.15		—		—
		15,728,376		$	12.82		32,558	$	22.32		16,523,015		$	13.72		173,114	$	21.83

Schedule of Share Authorized to be Issue and Available for Grant

The following number of shares were authorized to be issued and available for grant as of September 30, 2020 and September 30, 2019:

	September 30, 2020
	2017 Plan		2013 Plan
Shares authorized to be issued		2,945,443		2,047,269
Shares available for grant		1,233,266		—
	September 30, 2019
	2017 Plan		2013 Plan
Shares authorized to be issued		981,800		2,074,604
Shares available for grant		159,428		—

Schedule of Stock Compensation Expense

Total stock compensation expense for the Plans was as follows:

	Three Months Ended September 30,
	2020									2019
	2017 plan				2013 plan					2017 plan				2013 plan
	Options		Restricted Stock		Options			Total		Options		Restricted Stock		Options		Total
Cost of revenue	$	276	$	—	$	(5	)	$	271	$	278	$	—	$	97	$	375
Selling, general and administrative expense		592		233		53			878		185		111		384		680
	$	868	$	233	$	48		$	1,149	$	463	$	111	$	481	$	1,055

	Nine Months Ended September 30,
	2020								2019
	2017 plan				2013 plan				2017 plan				2013 plan
	Options		Restricted Stock		Options		Total		Options		Restricted Stock		Options		Total
Cost of revenue	$	973	$	—	$	126	$	1,099	$	623	$	—	$	390	$	1,013
Selling, general and administrative expense		1,178		973		189		2,340		457		323		1,784		2,564
	$	2,151	$	973	$	315	$	3,439	$	1,080	$	323	$	2,174	$	3,577

Summary of Weighted Average Assumptions Used in Black-Sholes Option-pricing Model

The following weighted-average assumptions were used in the Black-Sholes option-pricing model calculation for the nine months ended September 30, 2020 and September 30, 2019:

	September 30,		September 30,
	2020		2019
Common stock value (per share)	$	16.36	$	27.30
Expected volatility		46.14		47.94
Risk-free interest rate		0.41		2.15
Expected life (years)		7		7
Forfeiture rate	None		None
Dividend rate	None		None

Schedule of Common Stock Reserved for Future Issuance

Common Stock Reserved for Future Issuances—At September 30, 2020 and September 30, 2019, the Company has reserved certain stock of its authorized but unissued common stock for possible future issuance in connection with the following:

	September 30,		December 31,
	2020		2019
Warrants		116,350		650,590
Montrose 2013 Stock Incentive Plan		2,047,269		2,058,619
Montrose 2017 Stock Incentive Plan		2,945,443		997,785
Common stock reserved for future issuance		5,109,062		3,706,994

Montrose Amended & Restated 2017 Stock Incentive Plan

Summary of Stock Option Activity

The following summarizes the options activity of the 2017 Plan for the nine months ended September 30, 2020 and September 30, 2019:

	Options to Purchase Common Stock			Weighted- Average Exercise Price per Share		Weighted Average Grant Date Fair Value per Share		Weighted Average Remaining Contract Life (in Years)		Aggregate Intrinsic Value of In-The- Money Options (in Thousands)
Outstanding at December 31, 2018		257,762		$	20	$	10		-	$	1,151
Granted		356,470			27		14		-		—
Forfeited/ cancelled		(17,700	)		19		—		-		—
Outstanding at September 30, 2019		596,532			24		12		8.07		4,693
Outstanding at December 31, 2019		617,852			24		12		7.82		4,693
Granted		851,877			32		12		-		—
Forfeited/ cancelled		(14,375	)		22		—		-		—
Exercised		(925	)		14		—		-		7,918
Outstanding at September 30, 2020		1,454,429			21		12		7.59		7,649
Exercised at September 30, 2020		925			14		—		7.33		7,649
Options vested and expected to vest		1,454,429			21				9.04		7,649

Montrose Amended and Restated 2013 Stock Option Plan

Summary of Stock Option Activity

Montrose Amended & Restated 2013 Stock Option Plan—The following summarizes the activity of the 2013 Plan for the nine months ended September 30, 2020 and September 30, 2019:

	Options to Purchase Common Stock			Weighted- Average Exercise Price per Share		Weighted Average Grant Date Fair Value per Share		Weighted Average Remaining Contract Life (in Years)		Aggregate Intrinsic Value of In-The- Money Options (in Thousands)
Outstanding at December 31, 2018		1,900,404		$	6	$	1		7.30		33,290
Forfeited/ cancelled		(14,500	)		8		—		-		—
Expired		(5,400	)		8		—		-		—
Exercised		(19,010	)		6		—		-		466
Outstanding at September 30, 2019		1,861,494			6		1		6.65		47,381
Outstanding at December 31, 2019		1,855,469			6		1		6.40		46,617
Forfeited/ cancelled		(7,500	)		10		—		-		—
Expired		(11,300	)		6		—		-		—
Exercised		(19,175	)		8		—		-		354
Outstanding at September 30, 2020		1,817,494			6		1		5.63		33,772
Exercised at September 30, 2020		221,025			6		—		5.14		33,772
Options vested and expected to vest		1,817,494			6		—		5.17		33,772