Sec Form 4 Filing - GANTZ WILBUR H @ Aptinyx Inc. - 2018-06-25

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 GANTZ WILBUR H 2. Issuer Name and Ticker or Trading Symbol Aptinyx Inc. [ APTX] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O APTINYX INC., 909 DAVIS STREET, SUITE 600 3. Date of Earliest Transaction (MM/DD/YY) 06/25/2018 (Street) EVANSTON, IL60201 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ 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 06/25/2018 C 84,643 ( 1 ) A 193,265 I See footnote ( 2 ) Common Stock 06/25/2018 C 96,733 ( 1 ) A 289,998 I See footnote ( 2 ) Common Stock 06/25/2018 C 65,516 ( 1 ) A 355,514 I See footnote ( 2 ) Common Stock 06/25/2018 P 17,000 ( 4 ) A $ 16 372,514 I See footnote ( 2 ) Common Stock 06/25/2018 C 25,392 ( 1 ) A 25,392 I See footnote ( 3 ) Common Stock 06/25/2018 C 29,020 ( 1 ) A 54,412 I See footnote ( 3 ) Common Stock 06/25/2018 C 19,655 ( 1 ) A 74,067 I See footnote ( 3 ) Common Stock 06/25/2018 P 6,100 ( 4 ) A $ 16 80,167 I See footnote ( 3 )

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 Series A-1 Convertible Preferred Stock ( 1 ) 06/25/2018 C 2,334,966 ( 1 ) ( 1 ) Common Stock 84,643 ( 1 ) 0 I See Footnote ( 2 ) Series A-1 Convertible Preferred Stock ( 1 ) 06/25/2018 C 700,489 ( 1 ) ( 1 ) Common Stock 25,392 ( 1 ) 0 I See Footnote ( 3 ) Series A-2 Convertible Preferred Stock ( 1 ) 06/25/2018 C 2,668,508 ( 1 ) ( 1 ) Common Stock 96,733 ( 1 ) 0 I See Footnote ( 2 ) Series A-2 Convertible Preferred Stock ( 1 ) 06/25/2018 C 800,552 ( 1 ) ( 1 ) Common Stock 29,020 ( 1 ) 0 I See Footnote ( 3 ) Series B Convertible Preferred Stock ( 1 ) 06/25/2018 C 1,807,340 ( 1 ) ( 1 ) Common Stock 65,516 ( 1 ) 0 I See Footnote ( 2 ) Series B Convertible Preferred Stock ( 1 ) 06/25/2018 C 542,203 ( 1 ) ( 1 ) Common Stock 19,655 ( 1 ) 0 I See Footnote ( 3 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other GANTZ WILBUR H C/O APTINYX INC. 909 DAVIS STREET, SUITE 600 EVANSTON, IL60201 X Signatures /s/ Wilbur H. Gantz 06/26/2018 Signature of Reporting Person Date

Explanation of Responses :

( 1 )Each share of Series A-1 Convertible Preferred Stock, Series A-2 Convertible Preferred Stock and Series B Convertible Preferred Stock automatically converted into shares of Common Stock on a 27.58621-for-one basis immediately prior to the closing of the Issuer's initial public offering without payment or consideration. The shares of Series A-1 Convertible Preferred Stock, Series A-2 Convertible Preferred Stock and Series B Convertible Preferred Stock had no expiration date. ( 2 )The shares are held directly by Wilbur H. Gantz III Revocable Trust, of which the reporting person is the trustee. The reporting person disclaims beneficial ownership of the reported securities except to the extent of his pecuniary interest therein. ( 3 )The shares are held directly by LMC Holdings, LLC of which the reporting person is the manager. The reporting person disclaims beneficial ownership of the reported securities except to the extent of his pecuniary interest therein. ( 4 )On June 25, 2018, the Wilbur H. Gantz III Revocable Trust and LMC Holdings, LLC purchased 17,000 and 6,100 shares of common stock of the Issuer at a price of $16.00 per share, respectively, pursuant to an underwritten public offering.

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).

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