Sec Form 4 Filing - Flagship Ventures Fund 2007, L.P. @ Receptos, Inc. - 2013-11-14

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 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

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1. Name and Address of Reporting Person Flagship Ventures Fund 2007, L.P. 2. Issuer Name and Ticker or Trading Symbol Receptos, Inc. [ RCPT] 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) ONE MEMORIAL DRIVE, 7TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 11/14/2013 (Street) CAMBRIDGE, MA02142 4. If Amendment, Date Original Filed (MM/DD/YY) 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 (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 11/14/2013 S 155,583 D $ 25.03 ( 1 ) 1,768,755 D ( 4 ) Common Stock 11/15/2013 S 54,000 D $ 24.2 ( 2 ) 1,714,755 D ( 4 ) Common Stock 11/15/2013 S 904 D $ 25.1 1,713,851 D ( 4 ) Common Stock 11/18/2013 S 20,300 D $ 24.09 ( 3 ) 1,693,551 D ( 4 )

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 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 Flagship Ventures Fund 2007, L.P. ONE MEMORIAL DRIVE, 7TH FLOOR CAMBRIDGE, MA02142 X Flagship Ventures 2007 General Partner LLC ONE MEMORIAL DRIVE, 7TH FLOOR CAMBRIDGE, MA02142 X KANIA EDWIN M JR ONE MEMORIAL DRIVE, 7TH FLOOR CAMBRIDGE, MA02142 X AFEYAN NOUBAR ONE MEMORIAL DRIVE, 7TH FLOOR CAMBRIDGE, MA02142 X Signatures FLAGSHIP VENTURES FUND 2007, L.P. By: /s/ Noubar B. Afeyan Ph.D. 11/18/2013 Signature of Reporting Person Date FLAGSHIP VENTURES 2007 GENERAL PARTNER LLC By: /s/ Noubar B. Afeyan Ph.D. 11/18/2013 Signature of Reporting Person Date /s/ Edwin M. Kania, Jr. 11/18/2013 Signature of Reporting Person Date /s/ Noubar B. Afeyan Ph.D. 11/18/2013 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $25.00 to $25.50, inclusive. The reporting persons undertake to provide to Receptos Inc., any security holder of Receptos Inc., or the staff of the Securitites and Exchange Commision, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnotes 1, 2, and 3 to this Form 4. ( 2 )The price reported is a weighted average price. The shares were sold in multiple transactions at prices ranging from $24.10 to $24.50, inclusive. ( 3 )The price reported is a weighted average price. The shares were sold in multiple transactions at prices ranging from $24.00 to $24.25, inclusive. ( 4 )The shares of common stock are held by Flagship Ventures Fund 2007, L.P. ("Flagship Fund") The general partner of Flagship Fund is Flagship Ventures 2007 General Partner LLC ("Flagship GP"), and the managing members of Flagship GP are Noubar B. Afeyan Ph.D. and Edwin M. Kania, Jr. The General Partner and Messrs. Afeyan and Kania have voting and investment control over the shares held by Flagship Fund and may be deemed to be the beneficial owners of such shares and each of them disclaims beneficial ownership of the shares except to the extent of his or its pecuniary interest therein.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* 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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