Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F1,F2,F3	Feb 12, 2019	C	3,682,539	—	A	3,682,539	I	See footnotes
Common Stock^F1,F2,F3	Feb 12, 2019	C	345,419	—	A	4,027,958	I	See footnotes
Common Stock^F1,F3,F4	Feb 12, 2019	C	3,682,539	—	A	3,682,539	I	See footnotes
Common Stock^F1,F3,F4	Feb 12, 2019	C	345,419	—	A	4,027,958	I	See footnotes

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	—	Feb 12, 2019	C	16,571,429	D	—	—	Common Stock	3,682,539	I
Series A Preferred Stock^F1,F3,F4	—	Feb 12, 2019	C	16,571,428	D	—	—	Common Stock	3,682,539	I
Series B Preferred Stock^F1,F2,F3	—	Feb 12, 2019	C	1,554,388	D	—	—	Common Stock	345,419	I
Series B Preferred Stock^F1,F3,F4	—	Feb 12, 2019	C	1,554,388	D	—	—	Common Stock	345,419	I

Explanation of responses

F1The shares of the Issuer's Series A Preferred Stock and Series B Preferred Stock automatically converted into shares of the Issuer's Common Stock, for no additional consideration, at a ratio of 4.5 to one share, immediately prior to the consummation of the Issuer's initial public offering. The Series A Preferred Stock and Series B Preferred Stock had no expiration date.
F2These shares are directly held by ARCH Venture Fund IX, L.P. ("ARCH IX"). ARCH Venture Partners IX, L.P. ("GPLP"), as the sole general partner of ARCH IX, may be deemed to beneficially own the shares held by ARCH IX. ARCH Venture Partners IX, LLC ("GPLLC"), as the sole general partner of GPLP, may be deemed to beneficially own the shares held by GPLP. As managing directors of GPLLC, each of Keith Crandell, Clinton Bybee and Robert Nelsen (the "ARCH Managing Directors"), may be deemed to beneficially own the shares held by GPLLC.
F3Each of GPLP, ARCH Venture Partners IX Overage, L.P. ("Overage GPLP"), GPLLC and the ARCH Managing Directors disclaims beneficial ownership of the securities reported herein, except to the extent of their pecuniary interest therein, if any.
F4These shares are directly held by ARCH Venture Fund IX Overage, L.P. ("ARCH Overage"). Overage GPLP, as the sole general partner of ARCH Overage, may be deemed to beneficially own the shares held by ARCH Overage. GPLLC, as the sole general partner of Overage GPLP, may be deemed to beneficially own the shares held by Overage GPLP. As managing directors of GPLLC, each of the ARCH Managing Directors may be deemed to beneficially own the shares held by GPLLC.