Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F1,F2,F3	Nov 2, 2018	C	1,182,645	—	A	1,182,645	I	See footnote
Common Stock^F1,F2,F3	Nov 2, 2018	C	718,275	—	A	1,900,920	I	See footnote
Common Stock^F1,F2,F3	Nov 2, 2018	C	266,776	—	A	2,167,696	I	See footnote
Common Stock^F1,F2,F3	Nov 2, 2018	C	224,726	—	A	2,392,422	I	See footnote
Common Stock^F4,F2,F3	Nov 2, 2018	P	15,000	$14.00	A	2,407,422	I	See footnote
Common Stock^F1,F5,F3	Nov 2, 2018	C	894,146	—	A	894,146	I	See footnote
Common Stock^F4,F5,F3	Nov 2, 2018	P	60,000	$14.00	A	954,146	I	See footnote

Table II — derivative securities

Security	Conv. / exercise price	Date	Code	Shares	A/D	Exercisable	Expires	Underlying	Underlying shares	D/I
Series A Preferred Stock^F1,F2,F3,F6	—	Nov 2, 2018	C	1,182,645	D	—	—	Common Stock	1,182,645	I
Series B Preferred Stock^F1,F2,F3,F6	—	Nov 2, 2018	C	718,275	D	—	—	Common Stock	718,275	I
Series C Preferred Stock^F1,F2,F3,F6	—	Nov 2, 2018	C	266,776	D	—	—	Common Stock	266,776	I
Series D Preferred Stock^F1,F2,F3,F6	—	Nov 2, 2018	C	224,726	D	—	—	Common Stock	224,726	I
Series D Preferred Stock^F1,F5,F3,F6	—	Nov 2, 2018	C	894,146	D	—	—	Common Stock	894,146	I

Explanation of responses

F1Upon closing of the Issuer's initial public offering, each share of preferred stock was automatically converted into one share of the Issuer's common stock, for no additional consideration, on a 1:1 basis.
F2The shares are directly held by ARCH Venture Fund VII, L.P. ("ARCH Fund VII"). The sole general partner of ARCH Fund VII is ARCH Venture Partners VII, L.P. ("ARCH Partners VII"), which may be deemed to be the beneficial owner of the shares held by ARCH Fund VII. The sole general partner of ARCH Partners VII is ARCH Venture Partners VII, LLC ("ARCH VII LLC"), which may be deemed to be the beneficial owner of the shares held by ARCH Fund VII. ARCH Partners VII and ARCH VII LLC disclaim beneficial ownership of such shares, except to the extent of any pecuniary interest therein.
F3Clinton Bybee and Robert Nelsen are the managing directors of ARCH VII LLC and ARCH VIII LLC, and they may be deemed to beneficially own the shares held by ARCH Fund VII and ARCH Overage. Messrs. Bybee and Nelsen disclaim beneficial ownership of such shares, except to the extent of any pecuniary interest therein.
F4Reflects shares purchased in the Issuer's initial public offering.
F5The shares are directly held by ARCH Venture Fund VIII Overage, L.P. ("ARCH Overage"). The sole general partner of ARCH Overage is ARCH Venture Partners VIII, LLC ("AVP GPLLC"), which may be deemed to be the beneficial owner of the shares held by ARCH Overage. AVP GPLLC disclaims beneficial ownership of such shares, except to the extent of any pecuniary interest therein.
F6The expiration date is not relevant to the conversion of these securities.