X0206 3 2013-05-15 0 0001131543 AMBIT BIOSCIENCES CORP AMBI 0001055951 ORBIMED ADVISORS LLC 601 LEXINGTON AVENUE, 54TH FLOOR NEW YORK NY 10022 0 0 1 0 0001432241 OrbiMed Capital GP III LLC 601 LEXINGTON AVENUE, 54TH FLOOR NEW YORK NY 10022 0 0 1 0 0001055949 ISALY SAMUEL D 601 LEXINGTON AVENUE, 54TH FLOOR NEW YORK NY 10022 0 0 1 0 Common Stock, $0.001 par value per share 307 I See Footnotes Common Stock, $0.001 par value per share 2 I See Footnotes Series E Preferred Stock Common Stock 367315 I See Footnotes Series E Preferred Stock Common Stock 3498 I See Footnotes Series D-2 Preferred Stock Common Stock 219863 I See Footnotes Series D-2 Preferred Stock Common Stock 2094 I See Footnotes Series D Preferred Stock Common Stock 181689 I See Footnotes Series D Preferred Stock Common Stock 1730 I See Footnotes Series D-2 Preferred Stock Warrants (Right to Buy) 0.024 2011-05-18 2021-05-18 Common Stock 57217 I See Footnotes Series D-2 Preferred Stock Warrants (Right to Buy) 0.024 2011-05-18 2021-05-18 Common Stock 544 I See Footnotes Common Stock Warrants (Right to Buy) 0.24 2012-10-26 2022-10-26 Common Stock 559441 I See Footnotes Common Stock Warrants (Right to Buy) 0.24 2012-10-26 2022-10-26 Common Stock 5328 I See Footnotes Common Stock Warrants (Right to Buy) 36.96 2012-12-11 2020-09-29 Common Stock 1848 I See Footnotes Common Stock Warrants (Right to Buy) 36.96 2012-12-11 2020-09-29 Common Stock 17 I See Footnotes Common Stock Warrants (Right to Buy) 21.84 2012-12-11 2019-06-05 Common Stock 8540 I See Footnotes Common Stock Warrants (Right to Buy) 21.84 2012-12-11 2019-06-05 Common Stock 81 I See Footnotes Reflects a 1-for-24 reverse split of the Issuer's common stock effected on April 24, 2013. These shares of Series E convertible preferred stock, shares of Series D convertible preferred stock, shares of Series D-2 convertible preferred stock, shares of Common Stock, warrants to purchase Series D-2 convertible preferred stock and warrants to purchase Common Stock are held of record by OrbiMed Private Investments III, LP ("OPI") and may be deemed to be indirectly beneficially owned by OrbiMed Capital GP III LLC ("Capital"), OrbiMed Advisors LLC ("Advisors") and Samuel D. Isaly ("Isaly"). Capital is the sole general partner of OPI. Advisors, a registered adviser under the Investment Advisers Act of 1940, as amended, is the sole managing member of Capital. By virtue of such relationships, Capital and Advisors may be deemed to have voting and investment power with respect to the securities held by OPI noted above. Isaly, a natural person, may also be deemed to have voting and investment power with respect to the securities held by OPI noted above in his capacity as the managing member of, and holder of a controlling interest, in Advisors. As a result, each of Capital, Advisors and Isaly may be deemed to have beneficial ownership of the securities held by OPI. These shares of Series E convertible preferred stock, shares of Series D convertible preferred stock, shares of Series D-2 convertible preferred stock, shares of Common Stock, warrants to purchase Series D-2 convertible preferred stock and warrants to purchase Common Stock are held of record by OrbiMed Associates III, LP ("Associates") and may be deemed to be indirectly beneficially owned by Advisors and Isaly. Advisors is the sole general partner of Associates. Isaly is the managing member of, and holder of a controlling interest in, Advisors. By virtue of such relationships, Advisors and Isaly may be deemed to have voting and investment power with respect to the securities held by Associates noted above. As a result, each of Advisors and Isaly may be deemed to have beneficial ownership of the securities held by Associates. This report on Form 3 is jointly filed by Capital, Advisors and Isaly. Each of the Reporting Persons 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 or his pecuniary interest therein, if any. The Reporting Persons have designated a representative, currently David P. Bonita, an employee of Advisors, to serve on the Issuer's board of directors. This report shall not be deemed an admission that the Reporting Persons are beneficial owners for the purpose of Section 16 of the Exchange Act, or for any other purpose. The Series E Preferred Stock has no expiration date and is convertible at any time at the option of the holder and will automatically convert upon the closing of the Issuer's initial public offering, at a conversion ratio of 1 share of Common Stock for every 24 shares of Series E Preferred Stock, for no additional consideration. The Series D-2 Preferred Stock has no expiration date and is convertible at any time at the option of the holder and will automatically convert upon the closing of the Issuer's initial public offering, at a conversion ratio of 1 share of Common Stock for every 24 shares of Series D-2 Preferred Stock, for no additional consideration. The Series D Preferred Stock has no expiration date and is convertible at any time at the option of the holder and will automatically convert upon the closing of the Issuer's initial public offering, at a conversion ratio of 1 share of Common Stock for every 24 shares of Series D Preferred Stock, for no additional consideration. /s/ Samuel D. Isaly 2013-05-15