Mirum Pharma: A Rare Disease Growth Story to Watch

Key Points

• Mirum Pharmaceuticals posted strong revenue growth as its lead drug Livmarli continues gaining momentum.
• The company’s growing pipeline and commercial infrastructure could create multiple long-term growth opportunities.
• MIRM stock pulled back after earnings due to higher expenses and a convertible note offering, but analysts still see significant upside.

Mirum Pharmaceuticals NASDAQ: MIRM is a late-stage biotechnology company that is making significant progress toward its mission to combat rare diseases with no or limited treatment options. Mirum recently reported its Q1 2026 earnings, headlined by 43% year-over-year (YOY) revenue growth.

In 2025, the company reported revenue of $521.3 million, up 54%, with its lead drug Livmarli responsible for $360 million, a 69% YOY increase. Mirum has two other FDA-approved therapies—Cholbam for bile-acid synthesis disorders, and Ctexli for cerebrotendinous xanthomatosis, a rare genetic bile acid metabolism disorder.

The company also raised its full-year revenue guidance to a range of $660 million to $680 million. At the midpoint, that would be a YOY increase of 26%. However, since the earnings report, MIRM is down about 12% despite bullish analyst sentiment.

What Makes Mirum a Compelling Speculative Play?

Mirum's commercial story is unusual for a company that is not profitable: it already has three FDA-approved drugs generating real, growing revenue. As noted above, Livmarli remains the primary growth engine, with Q1 2026 net product sales of $159.9 million representing robust sequential momentum.

Livmarli is currently in a late-stage trial that could expand the drug’s label to include Alagille Syndrome. Topline data for Phase 3 is scheduled for December.

Cholbam and Ctexli provide a revenue floor that single-asset biotechs don't have.

The pipeline adds additional future revenue opportunities:

• Volixibat is in late-stage development for primary sclerosing cholangitis (PSC) and primary biliary cholangitis (PBC), two conditions with significant unmet need and sizable patient populations.

• Brelovitug targets chronic hepatitis delta, and zilurgisertib is already under FDA regulatory review for fibrodysplasia ossificans progressiva—a debilitating and currently untreatable rare bone disease.

Any one of these approvals could meaningfully expand the company's addressable market. Right now, Volixibat is the furthest along. On May 4, 2026, Mirum reported that the primary endpoint was met in the VISTAS Phase 2b study.

Then there's the commercial infrastructure advantage. Mirum has spent years building relationships with the hepatologists and transplant specialists who treat rare liver disease patients. That distribution moat is expensive to replicate and gives new pipeline drugs a faster path to adoption than a typical commercial-stage launch would suggest. For investors willing to wait, that foundation is the real asset.

Why Is MIRM Dropping?

The simple reason for MIRM's fall is that this is still a mid-cap company that is not profitable and, although revenue is growing, is still in the early stages. Short sellers are reacting to a specific data point in the earnings report, which is that the company’s operating expense was much higher in the quarter ($949 million) due mostly to one-time costs associated with its acquisition of Bluejay.

This highlights the primary risk with Mirum and many biotech stocks. The company needs to turn positive trial data into durable, reimbursed revenue. Mirum is doing that; now it must show that the revenue can grow in a way that makes the company profitable.

To that end, management said that its research and development (R&D) is funded and that it expects to be operating cash flow positive next year with GAAP profitability by 2028.

However, the more complex answer comes since the company proposed an offering of $600 million in convertible senior notes due 2032. The announcement came with an overallotment option for an additional $90 million, offered in private placement to qualified institutional buyers.

On the surface, there’s nothing too alarming about the announcement, nor will it necessarily be dilutive. And bullish investors can hypothesize that some of the money may go toward additional acquisitions for revenue-generating drugs.

The Post-Earnings Dip Can Be a Buyable Opportunity

Retail investors who bought into MIRM around the time it went public in 2019 have benefited from the company’s strong growth. In fact, in the past five years, MIRM is up more than 450%, including approximately 115% growth in the past 12 months.

It's a reminder that investors with patience and conviction can be rewarded when these companies execute, as Mirum certainly has. That raises the question of how much upside is still out there? The Mirum analyst forecasts on MarketBeat have a consensus price target of $137.08 as of May 19. That’s more than 40% above the stock’s price as of this writing.

Those ratings account for favorable topline readings for Maralizibat in late 2026. There’s also more upside in the company’s pipeline.

The catch? Short interest of around 17% means that there will be some selling pressure on any opportunity, even if it’s not foundational to Mirum’s bull case.