SEC Form 3

FORM 3

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

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1. Name and Address of Reporting Person* O'Donnell Niall (Last) (First) (Middle) C/O RIVERVEST VENTURE PARTNERS 101 SOUTH HANLEY ROAD, STE. 1850 (Street) ST. LOUIS MO 63105 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 07/17/2019	3. Issuer Name and Ticker or Trading Symbol Mirum Pharmaceuticals, Inc. [ MIRM ]
		4. Relationship of Reporting Person(s) to Issuer (Check all applicable) X Director 10% Owner Officer (give title below) Other (specify below)	5. If Amendment, Date of Original Filed (Month/Day/Year)
			6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	125,000	I	By RiverVest Venture Fund IV, L.P.(1)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Series A Preferred Stock	(2)	(2)	Common Stock	1,496,118(3)	(2)	I	By RiverVest Venture Fund IV, L.P.(1)

Explanation of Responses:

1. RiverVest Venture Partners IV, L.P. is the general partner of RiverVest Venture Fund IV, L.P. The Reporting Person is a manager of RiverVest Venture Partners IV, LLC, the sole general partner of RiverVest Venture Partners IV, L.P., and as a result may be deemed to share dispositive voting and investment power with respect to the shares held by RiverVest Venture Partners IV, L.P. The Reporting Person disclaims beneficial ownership of all shares held by RiverVest Venture Partners IV, L.P. except to the extent of his pecuniary interests therein.

2. The shares of Series A Preferred Stock have no expiration date and are convertible at any time at the election of the holder without payment of further consideration. Each share of Series A Preferred Stock will automatically convert into 0.125 shares of Common Stock upon the closing of the Issuer's initial public offering.

3. Share numbers give effect to the reverse split of each share of the Issuer's Common Stock into 0.125 shares of Common Stock effected on July 3, 2019, which will be effective for the Preferred Stock upon its conversion to Common Stock upon the closing of the Issuer's initial public offering.

Remarks:

	/s/ Jody Howe, Attorney-in-Fact	07/17/2019
	** Signature of Reporting Person	Date
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 5 (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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