FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL OMB Number: 3235-0287 Expires: January 31, 2005 Estimated average burden hours per response... 0.5

(Print or Type Responses)

1. Name and Address of Reporting Person * QVT Associates GP LLC   2. Issuer Name and Ticker or Trading Symbol ACHILLION PHARMACEUTICALS INC [ACHN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 1177 AVENUE OF THE AMERICAS, 9TH FLOOR 3. Date of Earliest Transaction (Month/Day/Year) 07/09/2013 (Street) NEW YORK, NY 10036 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) ___ Form filed by One Reporting Person _X_ Form filed by More than One Reporting Person (City) (State) (Zip) 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, $0.001 par value 07/09/2013   P   200,000 A $ 6.3 13,773,610 I Through QVT Fund IV LP, QVT Fund V LP and Quintessence Fund L.P. Common Stock, $0.001 par value 07/10/2013   P   100,000 A $ 6.35 13,873,610 I Through QVT Fund IV LP, QVT Fund V LP and Quintessence Fund L.P. Common Stock, $0.001 par value 07/10/2013   P   90,944 A $ 6.38 13,964,554 I Through QVT Fund IV LP, QVT Fund V LP and Quintessence Fund L.P.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
	Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.		SEC 1474 (9-02)

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 Underlying Securities (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 of Derivative Security: 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

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
QVT Associates GP LLC 1177 AVENUE OF THE AMERICAS 9TH FLOOR NEW YORK, NY 10036		X
QVT Fund V LP 1177 AVENUE OF THE AMERICAS 9TH FLOOR NEW YORK, NY 10036		X

Signatures

/s/ Tracy Fu, Managing Member		07/11/2013
**Signature of Reporting Person		Date

Explanation of Responses:

*	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).
Remarks: On July 9, 2013, QVT Fund IV LP purchased 25,244 shares of Common Stock, QVT Fund V LP purchased 152,989 shares of Common Stock and Quintessence Fund L.P. purchased 21,767 shares of Common Stock. On July 10, 2013, QVT Fund IV LP purchased 24,100 shares of Common Stock, QVT Fund V LP purchased 146,064 shares of Common Stock and Quintessence Fund L.P. purchased 20,780 shares of Common Stock. As a result, QVT Fund IV LP directly beneficially owns 1,794,660 shares of Common Stock, QVT Fund V LP directly beneficially owns 10,621,732 shares of Common Stock and Quintessence Fund L.P. directly beneficially owns 1,548,162 shares of Common Stock. QVT Associates GP LLC is the general partner of QVT Fund IV LP, QVT Fund V LP and Quintessence Fund L.P. (together with QVT Fund IV LP, and QVT Fund V LP, the "Funds"). QVT Financial LP is the investment manager for the Funds and therefore may be deemed the beneficial owner of the Common Stock held by the Funds. QVT Financial GP LLC is the general partner of QVT Financial LP and therefore may be deemed the beneficial owner of Common Stock beneficially owned by QVT Financial LP. The reporting person disclaims beneficial ownership of the reported securities except to the extent of its pecuniary interest therein.

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

Potential persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB number.