Sec Form 4 Filing - Arch Venture Fund VII LP @ Receptos, Inc. - 2014-05-13

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 Arch Venture Fund VII LP 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) 8725 WEST HIGGINS ROAD, SUITE 290 3. Date of Earliest Transaction (MM/DD/YY) 05/13/2014 (Street) CHICAGO, IL60631 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 05/13/2014 S 616 D $ 28.72 ( 1 ) 129,139 D ( 4 ) ( 6 ) Common Stock 05/13/2014 S 1,535 D $ 30.44 ( 2 ) 127,604 D ( 4 ) ( 6 ) Common Stock 05/14/2014 S 488 D $ 28.39 ( 3 ) 127,116 D ( 4 ) ( 6 ) Common Stock 05/13/2014 S 10,013 D $ 28.72 ( 1 ) 2,091,363 D ( 5 ) ( 6 ) Common Stock 05/13/2014 S 24,822 D $ 30.44 ( 2 ) 2,066,541 D ( 5 ) ( 6 ) Common Stock 05/14/2014 S 7,907 D $ 28.39 ( 3 ) 2,058,634 D ( 5 ) ( 6 )

Table II - Derivative Securities Acquired, Disposed of, o r 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 Arch Venture Fund VII LP 8725 WEST HIGGINS ROAD, SUITE 290 CHICAGO, IL60631 X ARCH Venture Partners VII, L.P. 8725 WEST HIGGINS ROAD, SUITE 290 CHICAGO, IL60631 X ARCH Venture Partners VII, LLC 8725 WEST HIGGINS ROAD, SUITE 290 CHICAGO, IL60631 X ARCH VENTURE FUND VI LP 8725 WEST HIGGINS ROAD, SUITE 290 CHICAGO, IL60631 X ARCH VENTURE PARTNERS VI LP 8725 WEST HIGGINS ROAD, SUITE 290 CHICAGO, IL60631 X ARCH VENTURE PARTNERS VI LLC 8725 WEST HIGGINS ROAD, SUITE 290 CHICAGO, IL60631 X CRANDELL KEITH 8725 WEST HIGGINS ROAD, SUITE 290 CHICAGO, IL60631 X BYBEE CLINTON 8725 WEST HIGGINS ROAD, SUITE 290 CHICAGO, IL60631 X NELSEN ROBERT 8725 WEST HIGGINS ROAD, SUITE 290 CHICAGO, IL60631 X Signatures /s/ Mark McDonnell - as Attorney-in-Fact for Keith Crandell, Managing Director of the general partner of the general partner of ARCH Fund VII 05/15/2014 Signature of Reporting Person Date /s/ Mark McDonnell - as Attorney-in-Fact for Keith Crandell, Managing Director of the general partner of ARCH Partners VII 05/15/2014 Signature of Reporting Person Date /s/ Mark McDonnell - as Attorney-in-Fact for Keith Crandell, Managing Director of ARCH VII LLC 05/15/2014 Signature of Reporting Person Date /s/ Mark McDonnell - as Attorney-in-Fact for Keith Crandell, Managing Director of the general partner of the general partner of ARCH Fund VI 05/15/2014 Signature of Reporting Person Date /s/ Mark McDonnell - as Attorney-in-Fact for Keith Crandell, Managing Director of the general partner of ARCH Partners VI 05/15/2014 Signature of Reporting Person Date /s/ Mark McDonnell - as Attorney-in-Fact for Keith Crandell, Managing Director of ARCH VI LLC 05/15/2014 Signature of Reporting Person Date /s/ Mark McDonnell - as Attorney-in-Fact for Keith Crandell 05/15/2014 Signature of Reporting Person Date /s/ Mark McDonnell - as Attorney-in-Fact for Clinton Bybee 05/15/2014 Signature of Reporting Person Date /s/ Mark McDonnell - as Attorney-in-Fact for Robert Nelsen 05/15/2014 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $28.60 to $29.60, inclusive. The reporting person takes to provide to RCPT, any security holder of RCPT, or the staff of the Securities and Exchange Commission, 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 in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $30.00 to $31.00, inclusive. ( 3 )The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $28.00 to $29.00, inclusive. ( 4 )Beneficial ownership consists of an aggregate of 127,116 shares of common stock held by ARCH Venture Fund VI, L.P. ("ARCH Fund VI"). The sole general partner of ARCH Fund VI is ARCH Venture Partners VI, L.P. ("ARCH Partners VI"), which may be deemed to beneficially own the shares held by ARCH Fund VI. The sole general partn er of ARCH Partners VI is ARCH Venture Partners VI, LLC ("ARCH VI LLC"), which may be deemed to beneficially own the shares held by ARCH Fund VI. ARCH Partners VI and ARCH VI LLC disclaim beneficial ownership of such shares, except to the extent of any pecuniary interest therein. ( 5 )Beneficial ownership consists of 2,058,634 shares of common stock held by ARCH Venture Fund VII, L.P. ("ARCH Fund VII"). The sole general partner of ARCH Fund VII is ARCH Venture Partners VII, L.P. ("ARCH Partners VII"), which may be deemed to be the beneficial owner of the shares held by ARCH Fund VII. The sole general partner of ARCH Partners VII is ARCH Venture Partners VII, LLC ("ARCH VII LLC"), which may be deemed to be the beneficial owner of the shares held by ARCH Fund VII. ARCH Partners VII and ARCH VII LLC disclaim beneficial ownership of such shares, except to the extent of any pecuniary interest therein. ( 6 )The managing directors of ARCH VI LLC and ARCH VII LLC are Keith Crandell, Clinton Bybee and Robert Nelsen, and they may be deemed to beneficially own the shares held by ARCH Fund VI and ARCH Fund VII. Messrs. Crandell, Bybee and Nelsen disclaim beneficial ownership of such shares, except to the extent of any 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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