X0306 4 2020-02-05 0 0001453593 Xtant Medical Holdings, Inc. XTNT 0001055951 ORBIMED ADVISORS LLC 601 LEXINGTON AVENUE 54TH FLOOR NEW YORK NY 10022 1 0 1 0 0001767936 Orbimed ROF II LLC 601 LEXINGTON AVE., 54TH FLOOR NEW YORK NY 10022 1 0 1 0 Common Stock, $0.000001 par value 2020-02-05 4 J 0 70423 0 A 91256 I See footnote Common Stock, $0.000001 par value 2020-02-05 4 J 0 70423 0 A 91256 I See footnote See Exhibit 99.1. These shares are subject to restricted stock unit awards granted under the Xtant Medical Holdings, Inc. 2018 Equity Incentive Plan, as amended, and will vest and become issuable with respect 35,211 shares on February 15, 2021 and with respect to 35,212 shares on February 15, 2022, conditioned upon Michael Eggenberg and Matthew Rizzo, respectively, remaining directors of Xtant through the vesting date. This report on Form 4 is jointly filed by Advisors and ROF II. Each of ROS Acquisition and ORO II disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein, if any. Advisors has designated certain representatives, including Matthew Rizzo and Michael Eggenberg, both of whom are employees of Advisors, to serve on Xtant's board of directors. This report shall not be deemed an admission that any such entity is a beneficial owner of such securities for the purposes of Section 16 of the Exchange Act or for any other purposes. See Exhibit 99.2. /s/ Sven H. Borho, Member of OrbiMed Advisors LLC 2020-02-07 /s/ Sven H. Borho, Member of OrbiMed ROF II LLC 2020-02-07 /s/ Carl L. Gordon, Member of OrbiMed Advisors LLC 2020-02-07 /s/ Carl L. Gordon, Member of OrbiMed ROF II LLC 2020-02-07 /s/ Jonathan T. Silverstein, Member of OrbiMed Advisors LLC 2020-02-07 /s/ Jonathan T. Silverstein, Member of OrbiMed ROF II LLC 2020-02-07