Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F1,F3,F5	May 7, 2018	C	2,030,625	—	A	2,070,172	I	See Footnote
Common Stock^F1,F3,F5	May 7, 2018	C	4,228,432	—	A	6,298,604	I	See Footnote
Common Stock^F1,F3,F5	May 7, 2018	C	2,067,160	—	A	8,365,764	I	See Footnote
Common Stock^F1,F4,F5	May 7, 2018	C	1,486,745	—	A	1,486,745	I	See Footnote
Common Stock^F1,F4,F5	May 7, 2018	C	195,672	—	A	1,682,417	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-1 Preferred Stock^F1,F3,F5,F2	—	May 7, 2018	C	2,030,625	D	—	—	Common Stock	2,030,625	I
Series A-2 Preferred Stock^F1,F3,F5,F2	—	May 7, 2018	C	4,228,432	D	—	—	Common Stock	4,228,432	I
Series B Preferred Stock^F1,F3,F5,F2	—	May 7, 2018	C	2,067,160	D	—	—	Common Stock	2,067,160	I
Series B Preferred Stock^F1,F4,F5,F2	—	May 7, 2018	C	1,486,745	D	—	—	Common Stock	1,486,745	I
Series C Preferred Stock^F1,F4,F5,F2	—	May 7, 2018	C	195,672	D	—	—	Common Stock	195,672	I

Explanation of responses

F1The shares of the Issuer's Preferred Stock automatically converted into shares of the Issuer's Common Stock, for no additional consideration, on a 1:1 basis immediately prior to the consummation of the Issuer's initial public offering.
F2The expiration date is not relevant to the conversion of these securities.
F3The shares are directly held by ARCH Venture Fund VII, L.P. ("ARCH VII"). ARCH Venture Partners VII, L.P. (the "GPLP"), as the sole general partner of ARCH VII, may be deemed to beneficially own certain of the shares held by ARCH VII. ARCH Venture Partners VII, LLC ("GPLLC"), as the sole general partner of GPLP, may be deemed to beneficially own the shares held by GPLP. GPLP and GPLLC disclaim beneficial ownership of such shares, except to the extent of any pecuniary interest therein.
F4The shares are directly held by ARCH Venture Fund VIII Overage, L.P. ("ARCH Overage"). ARCH Venture Partners VIII, LLC (the "AVP GPLLC"), as the sole general partner of ARCH Overage, may be deemed to beneficially own the shares held by ARCH Overage. AVP GPLLC disclaims beneficial ownership of such shares, except to the extent of any pecuniary interest therein.
F5The managing directors of GPLLC and AVP GPLLC are Keith Crandell and Clinton Bybee, and they may be deemed to beneficially own the shares held by ARCH Fund VII and ARCH Overage. Messrs. Crandell and Bybee disclaim beneficial ownership of such shares, except to the extent of any pecuniary interest therein.