Company: MIRM
Filing Date: 2025-08-12
Form Type: S-3ASR
Source: 0001193125-25-178937
Chunk: 3

Company: Mirum Pharmaceuticals, Inc.
Filing Date: 2025-08-12
Form: S-3ASR
Chunk 3
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 high degree of risk. You should review carefully the risks and uncertainties described under the heading “ Risk Factors” on page 7 of this prospectus as well as those contained in the applicable prospectus supplement and any related free writing prospectus, and under similar headings in the other documents that are incorporated by reference into this prospectus.

NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES COMMISSION HAS APPROVED OR DISAPPROVED OF THESE SECURITIES OR DETERMINED IF THIS PROSPECTUS IS TRUTHFUL OR COMPLETE. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.

The date of this prospectus is August 12, 2025

TABLE OF CONTENTS

|                                                   |     | Page |    |
| ABOUT THIS PROSPECTUS                             |     |      |  1 |
| PROSPECTUS SUMMARY                                |     |      |  2 |
| RISK FACTORS                                      |     |      |  7 |
| SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS |     |      |  8 |
| USE OF PROCEEDS                                   |     |      | 10 |
| DESCRIPTION OF CAPITAL STOCK                      |     |      | 11 |
| DESCRIPTION OF DEBT SECURITIES                    |     |      | 15 |
| DESCRIPTION OF WARRANTS                           |     |      | 22 |
| LEGAL OWNERSHIP OF SECURITIES                     |     |      | 25 |
| PLAN OF DISTRIBUTION                              |     |      | 29 |
| LEGAL MATTERS                                     |     |      | 31 |
| EXPERTS                                           |     |      | 31 |
| WHERE YOU CAN FIND MORE INFORMATION               |     |      | 31 |
| INCORPORATION OF CERTAIN INFORMATION BY REFERENCE |     |      | 32 |

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ABOUT THIS PROSPECTUS

This prospectus is a part of an automatic registration statement on Form S-3 that we filed with the
U.S. Securities and Exchange Commission, or the SEC, utilizing a “shelf” registration process as a “well-known seasoned issuer,” as defined in Rule 405 under the Securities Act of 1933, as amended, or the Securities Act. Under
this shelf registration process, we may offer and sell from time to time in one or more offerings any combination of the securities described in this prospectus. No limit exists on the aggregate number or amount of securities we may sell pursuant