James E. Flynn - 01 Jun 2021 Form 4 Insider Report for Singular Genomics Systems, Inc.

Footnote F1

Each share of Series B Preferred Stock automatically converted into one share of the Issuer's common stock upon the closing of the Issuer's initial public offering.

Footnote F2

The 6% Convertible Note due 2023 held by Deerfield Private Design Fund IV, L.P. ("Fund IV") automatically converted into shares of the Issuer's common stock upon the closing of the Issuer's initial public offering.

Footnote F3

The 6% Convertible Note due 2023 held by Deerfield Partners, L.P. ("Deerfield Partners") automatically converted into shares of the Issuer's common stock upon the closing of the Issuer's initial public offering.

Footnote F4

No transaction is being reported at this time. This line is only reporting holdings as of the date hereof.

Footnote F5

The option granted to Andrew ElBardissi and reported herein is held for the benefit, and at the direction, of Deerfield Management Company, L.P. ("Deerfield Management").

Footnote F6

This Form 4 is being filed by the undersigned as well as the entities listed on the Joint Filer Information Statement attached as an exhibit hereto (the "Reporting Persons"). Deerfield Mgmt IV, L.P. is the general partner of Fund IV. Deerfield Mgmt, L.P. is the general partner of Deerfield Partners (collectively with Fund IV, the "Funds"). Deerfield Management is the investment manager of the Funds. James E. Flynn is the sole member of the general partner of each of Deerfield Mgmt IV, L.P., Deerfield Mgmt, L.P. and Deerfield Management.

Footnote F7

In accordance with Instruction 4 (b)(iv) to Form 4, the entire amount of the Issuer's securities held by the Funds is reported herein. For purposes of Section 16 of the Securities Exchange Act of 1934, as amended, each Reporting Person disclaims beneficial ownership of any such securities, except to the extent of his/its indirect pecuniary interest therein, if any, and this report shall not be deemed an admission that such Reporting Person is the beneficial owner of such securities for purposes of Section 16 or otherwise.