Stockholder’s equity (deficit) (Tables)

12 Months Ended

Dec. 31, 2019

Stockholder’s equity (deficit)

Schedule of common stock reserved for issuance

	December 31,
	2019	2018
Conversion of outstanding shares of preferred stock	—	21,056,136
Options outstanding under the 2018 Stock Option and Grant Plan	2,296,029	1,839,913
Options outstanding under the 2019 Stock Option and Incentive Plan	800,526	—
Options available for future grant	1,771,931	1,219,461
2019 Employee Stock Purchase Plan	269,364	—
	5,137,850	24,115,510

Summary of restricted stock activity

The following table summarizes restricted stock activity since December 31, 2017:

		Grant-Date Fair
	Number of Shares	Value
Unvested restricted common stock as of December 31, 2017	226,400	$	—
Shares vesting	(146,210)		—
Unvested restricted common stock as of December 31, 2018	80,190		—
Early exercise of unvested stock options	491,207		0.65
Shares vesting	(416,248)		0.65
Unvested restricted common stock as of December 31, 2019	155,149	$	0.65