SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* Marchington Allan P (Last) (First) (Middle) C/O AMBIT BIOSCIENCES CORPORATION 11080 ROSELLE STREET (Street) SAN DIEGO CA 92121 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol AMBIT BIOSCIENCES CORP [ AMBI ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X Director 10% Owner Officer (give title below) Other (specify below)
	3. Date of Earliest Transaction (Month/Day/Year) 05/21/2013
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	05/21/2013		C		281,624	A	(1)	281,847	I	See Footnote(2)
Common Stock	05/21/2013		C		307,051	A	(3)	588,898	I	See Footnote(2)
Common Stock	05/21/2013		C		306,619	A	(4)	895,517	I	See Footnote(2)
Common Stock	05/21/2013		P		431,527(6)	A	$8	1,327,044	I	See Footnote(2)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Series D Preferred Stock	(1)	05/21/2013		C			3,058,909	(1)	(1)	Common Stock	281,624	$0.00	0	I	See Footnote(2)
Series D-2 Preferred Stock	(3)	05/21/2013		C			7,369,222	(3)	(3)	Common Stock	307,051	$0.00	0	I	See Footnote(2)
Series E Preferred Stock	(4)	05/21/2013		C			7,358,848	(4)	(4)	Common Stock	306,619	$0.00	0	I	See Footnote(2)
Stock Option (right to buy)	$6.66	05/21/2013		A			7,085	(5)	05/20/2023	Common Stock	7,085	$0.00	7,085	D

Explanation of Responses:

1. Upon the closing of the Issuer's initial public offering, every 10.86166 shares of Series D Preferred Stock automatically converted into 1 share of Common Stock for no additional consideration and had no expiration date. The conversion ratio was incorrectly stated in the Reporting Person's Form 3.

2. The securities are held by Apposite Healthcare Fund LP, or Apposite. Apposite Healthcare (GP) Limited, the general partner of Apposite, has appointed Apposite Capital LLP as the manager of Apposite. The Reporting Person is a designated member of Apposite Capital LLP and, together with F. David Porter and Stephen Adkin, the other designated members of Apposite Capital LLP, shares voting and investment control over the securities held by Apposite; however, each disclaims beneficial ownership, except to the extent of their pecuniary interests therein.

3. Upon the closing of the Issuer's initial public offering, every 24 shares of Series D-2 Preferred Stock automatically converted into 1 share of Common Stock for no additional consideration and had no expiration date.

4. Upon the closing of the Issuer's initial public offering, every 24 shares of Series E Preferred Stock automatically converted into 1 share of Common Stock for no additional consideration and had no expiration date.

5. One-third of the shares will vest on the first, second and third year anniversaries of the date of grant, such that the stock option is fully vested on May 21, 2016, subject to the optionee's continuous service with the Issuer through such vesting date.

6. The shares were purchased by Apposite in a private placement concurrent with the closing of the Issuers' initial public offering.

	/s/ Allan P. Marchington	05/21/2013
	** Signature of Reporting Person	Date
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* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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