Mirum Pharmaceuticals, Inc. 8-K

What Happened

• Mirum Pharmaceuticals, Inc. announced the issuance on May 15, 2026 of $690.0 million aggregate principal amount of 0.00% Convertible Senior Notes due 2032 (the Notes), which includes the full exercise of an initial purchasers’ option to buy an extra $90.0 million. The company filed an 8‑K on May 18, 2026 and previously issued press releases on May 12, 2026 announcing the launch and pricing of the offering.

Key Details

• Offering size and net proceeds: $690.0M principal issued; estimated net proceeds ~ $671.6M after fees and expenses.
• Use of proceeds: ~ $475.0M expected to be used to pay the cash portion of concurrent Note Exchange Transactions and the remainder for general corporate purposes; company expects to issue 3,220,529 shares in exchange for ~ $237.2M principal of its 4.00% convertible notes due 2029.
• Note economics and terms: 0.00% annual interest (no regular interest, principal will not accrete); maturity date June 1, 2032; initial conversion rate 7.1971 shares per $1,000 principal (implied conversion price ≈ $138.94/share). Company may settle conversions in cash, stock, or a combination.
• Conversion and redemption mechanics: conversion rights are limited to specified windows (including triggered windows tied to the company’s stock price and other events), with broader conversion availability from March 1, 2032 through two business days before maturity; company may redeem notes on or after June 6, 2029 subject to conditions (including market‑price tests and a minimum remaining outstanding amount).
• Credit and protections: the Notes are senior, unsecured obligations governed by an indenture with U.S. Bank Trust Company, N.A. as trustee; holders have customary events‑of‑default and may require repurchase on certain “Fundamental Change” events.

Why It Matters

• Funding and balance sheet: the transaction raises significant non‑dilutive cash now (zero coupon) to support Mirum’s corporate needs and to facilitate the exchange of existing 2029 convertible debt, reducing near‑term cash interest obligations.
• Potential dilution and conversion risk: although the Notes initially do not bear interest, they are convertible into common stock (or cash/combination at the company’s election). If conversions occur, shareholders could see dilution—initial conversion implies 7.1971 shares per $1,000 note ($138.94/share). Conversion is subject to price and other conditions, so dilution timing is uncertain.
• Investor protections and optionality: the indenture contains standard protections (events of default, repurchase rights on certain corporate changes) and also restricts the company’s ability to redeem or partially redeem the Notes under specified conditions, which may affect future capital strategy.

Keywords: convertible notes, debt offering, Mirum Pharmaceuticals, 0% notes, convertible senior notes, dilution, financing, 2032 maturity.