GOLDMAN SACHS GROUP INC bought ATTO

Footnotes

The previous report on Form 3 reflected an administrative error with respect to the number of shares of common stock issuable upon conversion of the Preferred Stock, which is corrected in this Form 4.; All shares of the Issuer's redeemable convertible preferred stock automatically converted into shares of the Issuer's common stock on a 1-for-1 basis, adjusted for a 1-for-9.29 reverse stock split effected by the Issuer on July 29, 2026, upon the completion of the Issuer's initial public offering (the "IPO").; Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein except to the extent of its pecuniary interest therein, if any, and this report shall not be deemed an admission that any such Reporting Person is the beneficial owner of, or has any pecuniary interest in, such securities for purposes of Section 16 of the Exchange Act, or for any other purpose.; This statement is being filed by Goldman Sachs Group, Inc. ("GS Group"), GS&Co, Goldman Sachs Asset Management, L.P. ("GSAM LP"), Broad Street Principal Investments L.L.C. ("BSPI"), which directly holds 96,190 shares of common stock purchased in the IPO and 468,565 shares of common stock converted from 3,497,806 shares of Series B Preferred Stock and 855,179 shares of Series C Preferred Stock, WSLS Offshore Investments, SLP ("WSLS Offshore"), which directly holds 131,283 shares of common stock purchased in the IPO and 639,518 shares of common stock converted from 4,773,948 shares of Series B Preferred Stock and 1,167,182 shares of Series C Preferred Stock, West Street Life Sciences I, L.P. ("WSLS I"), which directly holds 137,708 shares of common stock purchased in the IPO and 670,812 shares of common stock converted from 5,007,564 shares of Series B Preferred Stock and 1,224,299 shares of Series C Preferred Stock,... (continued in footnote 7); (continued from footnote 6)...WSLS Emp Offshore Investments, L.P. ("WSLS Emp Offshore"), which directly holds 36,927 shares of common stock purchased in the IPO and 179,879 shares of common stock converted from 1,342,794 shares of Series B Preferred Stock and 328,300 shares of Series C Preferred Stock, and WSLS Emp Onshore Investments, L.P. ("WSLS Emp Onshore"), which directly holds 97,892 shares of common stock purchased in the IPO and 476,858 shares of common stock converted from 3,559,718 shares of Series B Preferred Stock and 870,315 shares of Series C Preferred Stock. GS&Co is a direct subsidiary of GS Group and is the manager of BSPI. WSLS Offshore, WSLS I, WSLS Emp Offshore, and WSLS Emp Onshore are investment vehicles managed by GSAM LP, an indirect subsidiary of GS Group.