Company: MIRM
Filing Date: 2025-08-12
Form Type: S-3ASR
Source: 0001193125-25-178937
Chunk: 55

Company: Mirum Pharmaceuticals, Inc.
Filing Date: 2025-08-12
Form: S-3ASR
Chunk 55
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| • |     | 25,177 shares of our common stock reserved for issuance under our Inducement Plan as of June 30, 2025. |

To the extent that options outstanding as of June 30, 2025 have been or are exercised, restricted or performance stock units are vested and settled, convertible notes have been or are converted, or other shares are issued, investors purchasing shares in this offering could experience further dilution. In addition, we may choose to raise additional capital due to market conditions or strategic considerations, including for potential acquisition or in-licensingopportunities, even if we believe we have sufficient funds for our current or future operating plans. To the extent that additional capital is raised through the sale of equity or convertible debt securities, the issuance of these securities could result in further dilution to our stockholders. S-12

PLAN OF DISTRIBUTION

We have entered into a sales agreement with Leerink Partners and Cantor under which we may issue and sell up to $200,000,000 of shares of our
common stock from time to time through Leerink Partners and Cantor as our sales agents. Sales of our common stock, if any, will be made by any method that is deemed to be an “at the market offering” as defined in Rule 415(a)(4) under the
Securities Act, including sales made directly on or through the Nasdaq Global Market, on or through any other existing trading market for the common stock or to or through a market maker.

The sales agents will offer our common stock subject to the terms and conditions of the sales agreement on a daily basis or as otherwise
agreed upon by us and the sales agents. We will designate the maximum number or amount of common stock to be sold through the sales agents on a daily basis or otherwise determine such maximum number or amount together with the sales agents. Subject
to the terms and conditions of the sales agreement, the sales agents will use commercially reasonable efforts consistent with their normal trading and sales practices to sell on our behalf all of the common stock requested to be sold by us. We may
instruct the sales agents not to sell common stock if the sales cannot be effected at or above a minimum price designated by us in any such instruction. We or the sales agents may suspend the offering of our common stock being made through the sales
agents under the sales agreement upon proper notice to the other parties. We and the sales agents each have the right, by giving written notice as specified in the