Summary of significant accounting policies (Tables)

12 Months Ended

Dec. 31, 2020

Summary of significant accounting policies

Schedule of money market funds and marketable securities

Cash, cash equivalents, and marketable securities as of December 31, 2020 and 2019 consist of the following:

	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
	(in thousands)
As of December 31, 2020
Money market funds included in cash and cash equivalents	$	103,992	$	—	$	—	$	103,992
Marketable securities:
U.S. Treasury notes		70,348		—		6		70,342
Equity securities		1,220		5,136		—		6,356
Total marketable securities	$	71,568	$	5,136	$	6	$	76,698
Total money market funds and marketable securities	$	175,560	$	5,136	$	6	$	180,690
As of December 31, 2019
Money market funds included in cash and cash equivalents	$	78,303	$	—	$	—	$	78,303
Marketable securities:
U.S. Treasury notes		195,467		52		28		195,491
Equity securities		1,220		700		—		1,920
Total marketable securities	$	196,687	$	752	$	28	$	197,411
Total money market funds and marketable securities	$	274,990	$	752	$	28	$	275,714

Reconciliation of cash, cash equivalents, and restricted cash

	As of December 31,
	2020		2019		2018
	(in thousands)
Cash and cash equivalents	$	104,440	$	86,042	$	46,859
Restricted cash included in deposits and other noncurrent assets		1,779		735		735
Total cash, cash equivalents, and restricted cash	$	106,219	$	86,777	$	47,594

Outstanding potentially dilutive securities excluded in the calculation of diluted net loss per share

The following table sets forth the outstanding potentially dilutive securities that have been excluded in the calculation of diluted net income (loss) per share because to do so would be anti-dilutive:

	As of December 31,
	2020	2019	2018
Unvested restricted common stock awards	156,863	176,471	235,294
Unvested restricted common stock units	527,625	455,404	—
Outstanding stock options	5,379,856	5,317,326	4,225,152
Total	6,064,344	5,949,201	4,460,446

Schedule of weighted average number of shares, basic and diluted

	Year Ended December 31,
	2020		2019		2018
	(in thousands, except share data)
Numerator:
Net income (loss)	$	36,741	$	(43,597)	$	(88,288)
Denominator for basic net income (loss) per share:
Weighted average shares outstanding-basic		37,132,447		35,898,266		32,065,781
Denominator for diluted net income (loss) per share:
Weighted average shares outstanding		37,132,447		35,898,266		32,065,781
Common stock options and restricted stock units		216,068		—		—
Weighted average shares outstanding-diluted		37,348,514		35,898,266		32,065,781