Sec Form 3 Filing - USMAN NASSIM @ Principia Biopharma Inc. - 2018-09-13

FORM 3 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 USMAN NASSIM 2. Issuer Name and Ticker or Trading Symbol Principia Biopharma Inc. [ PRNB] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O PRINCIPIA BIOPHARMA INC., 400 EAST JAMIE COURT, SUITE 302 3. Date of Earliest Transaction (MM/DD/YY) 09/13/2018 (Street) SOUTH SAN FRANCISCO, CA94080 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

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 Preferred Stock $ 0 ( 1 ) ( 1 ) Common Stock 1,070,771 I See footnote ( 2 ) Series B-1 Preferred Stock $ 0 ( 1 ) ( 1 ) Common Stock 312,741 I See footnote ( 2 ) Series B-2 Preferred Stock $ 0 ( 1 ) ( 1 ) Common Stock 260,617 I See footnote ( 2 ) Series B-3 Preferred Stock $ 0 ( 1 ) ( 1 ) Common Stock 544,047 I See footnote ( 2 ) Series C Preferred Stock $ 0 ( 1 ) ( 1 ) Common Stock 6,949 I See footnote ( 2 ) Warrant to Purchase Series B-3 Preferred Stock $ 8.9931 ( 3 ) 12/29/2022 Series B-3 Preferred Stock ( 1 ) 28,623 I See footnote ( 2 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other USMAN NASSIM C/O PRINCIPIA BIOPHARMA INC. 400 EAST JAMIE COURT, SUITE 302 SOUTH SAN FRANCISCO, CA94080 X X Signatures Nassim Usman, by /s/ Ron Metzger, Attorney-in-Fact 09/13/2018 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Each share of Preferred Stock will be automatically converted into one (1) share of Common Stock, for no additional consideration, immediately prior to the consummation of the Issuer's initial public offering, and has no expiration date. ( 2 )The securities are held by Morgenthaler Venture Partners IX, L.P. ("MVP IX"). The General Partner of MVP IX is Morgenthaler Management Partners IX, LLC ("MMP IX"). MMP IX may be deemed to indirectly beneficially own the securities held directly by MVP IX. Reporting Person is a venture partner at MMP IX and may be deemed to have an indirect pecuniary interest in these shares. Reporting Person disclaims beneficial ownership of the shares held of record by MVP IX except to the extent of his pecuniary interest therein. Reporting Person does not have voting or dispositive power over the shares. ( 3 )This warrant is exercisable at any time.

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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