Stockholder's Equity (Deficit) (Tables)

3 Months Ended

Mar. 31, 2021

Summary of Issued Shares of Common Stock

The Company issued the following shares of common stock:

	Three Months Ended March,
	2021				2020
	Shares		Average Price per Share		Shares		Average Price per Share
Acquisitions		71,740	$	31.65		—	$	—
Exercise of warrants		67,713		17.19		—		—
Exercise of options		330,060		6.62		—		—
Restricted shares, net		36,817		29.88		—		—
Total		506,330	$	13.27		—	$	—

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:

	March 31, 2021
	2017 Plan		2013 Plan		Total
Shares authorized to be issued		3,944,750		2,047,269		5,992,019
Shares available for grant		1,618,996		—		1,618,996
	March 31, 2020
	2017 Plan		2013 Plan		Total
Shares authorized to be issued		1,057,785		2,058,619		3,116,404
Shares available for grant		8,217		4,775		12,992

Schedule of Stock Compensation Expense

Total stock compensation expense for the Plans was as follows:

	Three Months Ended March 31,
	2021								2020
	2017 plan				2013 plan				2017 plan				2013 plan
	Options		Restricted Stock		Options		Total		Options		Restricted Stock		Options		Total
Cost of revenue	$	606	$	—	$	10	$	616	$	355	$	—	$	70	$	425
Selling, general and    administrative expense		1,004		182		3		1,189		287		370		68		725
Total	$	1,610	$	182	$	13	$	1,805	$	642	$	370	$	138	$	1,150

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:

	March 31,			March 31,
	2021			2020
Common stock value (per share)	$ 37.61			$ 31.60
Expected volatility		58.01	%		31.87	%
Risk-free interest rate		0.71	%		1.78	%
Expected life (years)	5.5-7.0			7.0
Forfeiture rate	None			None
Dividend rate	None			None

Schedule of Common Stock Reserved for Future Issuance

Common Stock Reserved for Future Issuances—The Company has reserved certain stock of its authorized but unissued common stock for possible future issuance in connection with the following:

	March 31,
	2021		2020
Warrants		—		650,590
Montrose 2013 Stock Incentive Plan		2,047,269		2,058,619
Montrose 2017 Stock Incentive Plan		3,944,750		1,057,785
Common stock reserved for future issuance		5,992,019		3,766,994

Montrose Amended & Restated 2017 Stock Incentive Plan

Summary of Stock Option Activity

The following summarizes the options activity of the 2017 Plan:

	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 January 1, 2020		617,852		$	24	$	12		7.82	$	4,696
Granted		158,062			32		12		—		—
Forfeited/ cancelled		(2,000	)		32		—		—		—
Outstanding at March 31, 2020		773,914			26		12		8.50		4,693
Outstanding at January 1, 2021		1,840,229			23		12		9.09		15,598
Granted		224,270			38		20		—		—
Forfeited/ cancelled		(10,000	)		26		—		—		—
Expired		(1,250	)		18		—		—		—
Exercised		(17,188	)		16		—		—		519
Outstanding at March 31, 2021		2,036,061			24		13		8.97		52,317
Exercisable at March 31, 2021		218,379			24		—		7.79		5,702
Options vested and expected to vest		2,036,061			24		—		8.97		52,317

Montrose Amended and Restated 2013 Stock Option Plan

Summary of Stock Option Activity

The following summarizes the activity of the 2013 Plan:

	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 January 1, 2020		1,855,469		$	6	$	1		6.14		46,617
Expired		(725	)		6		—		—		—
Outstanding at March 31, 2020		1,854,744			6		1		6.14		46,521
Outstanding at January 1, 2021		1,787,869			6		—		5.40		43,867
Exercised		(311,872	)		6		—		—		12,321
Outstanding at March 31, 2021		1,475,997			6		—		5.14		64,492
Exercisable at March 31, 2021		1,456,922			6		—		5.13		63,740
Options vested and expected to vest		1,475,997			6		—		5.14		64,492