Mirum Pharmaceuticals, Inc. (MIRM) Stock Price & How to Invest

Mirum Pharmaceuticals develops and sells medicines for rare liver and metabolic diseases, conditions that affect small patient populations but have almost no alternatives. Three products carry the revenue. LIVMARLI (maralixibat) is an ileal bile acid transporter inhibitor approved for Alagille syndrome and progressive familial intrahepatic cholestasis, and it did about $128.7 million in the second quarter of 2026, up roughly 46% year over year. CHOLBAM (cholic acid) treats bile-acid synthesis disorders, and CTEXLI (chenodiol), approved in early 2025, is the first and only therapy specifically cleared for cerebrotendinous xanthomatosis in adults. Those two are reported together as bile acid medicines and contributed about $47.5 million in the quarter, up roughly 20%. Total net product sales reached about $176.2 million in Q2 2026, a gain of roughly 38%, and management raised full-year 2026 guidance to $680 million to $700 million after starting the year at $630 million to $650 million.

The investment picture is a commercial business funding a large, event-heavy pipeline. Mirum closed a $620 million acquisition of Bluejay Therapeutics in January 2026 ($250 million cash plus $370 million in stock, with up to $200 million in sales milestones), which brought in brelovitug, a Phase 3 antibody for chronic hepatitis delta virus. It also licensed zilurgisertib, an oral ALK2 inhibitor for fibrodysplasia ossificans progressiva, from Incyte, with an FDA target action date of September 26, 2026. The accounting consequence is severe: the Bluejay deal produced a roughly $726 million in-process R&D charge in the first quarter, so trailing net loss screens near $860 million even though the underlying product business is scaling. The other consequence showed up on August 5, 2026, when the company disclosed that the FDA recommended a Phase 3 study of volixibat in primary sclerosing cholangitis despite a Phase 2b trial that met its primary endpoint. That pushed the filing to the first half of 2027 and shares fell roughly 10% to 15% the next session to about $94, against a 52-week range of roughly $50 to $130. Cash stood at about $561 million at the end of June 2026.

The August 2026 volixibat decision is the clearest illustration of the risk: a Phase 2b study met its primary endpoint and had Breakthrough Therapy designation, and the FDA still recommended a full Phase 3, pushing an NDA to the first half of 2027 and knocking roughly 10% to 15% off the stock in a session. Reported profitability is deeply negative because of the roughly $726 million in-process R&D charge from the Bluejay acquisition, so trailing GAAP earnings and price-to-earnings screens are effectively meaningless here and any valuation work has to run off revenue and cash. Revenue is concentrated: LIVMARLI alone is roughly three quarters of product sales, and it competes directly with Ipsen's Bylvay in the same small patient populations, where a payer formulary decision or a safety label change can move share quickly. Rare-disease pricing carries persistent policy and reimbursement exposure, and the addressable populations are measured in thousands of patients rather than millions, so a single failed diagnosis-expansion effort matters. The zilurgisertib and brelovitug programs are unapproved assets purchased or licensed at real cost, and neither has generated a dollar of revenue.

14 analysts publish price targets on MIRM, averaging $146.50 against a $94.11 price as of August 2026, or +55.7%. The published targets run from $125.00 to $185.00, a moderate spread, and the ratings split 13 buy, 0 hold, 0 sell. Over the last six months there have been 7 raises and 3 cuts among the published actions. A price target is what an analyst published on a date, not a prediction, and sell-side ratings skew positive across the whole market.

Read the full MIRM forecast and price target for the target table, the recent rating actions by firm, and how the consensus has shifted.

We give no verdict on Mirum Pharmaceuticals, Inc.. Both cases are real, which is why the question is contested at all, so here is the strongest version of each.

The case for buying. LIVMARLI compounding in two approved indications. LIVMARLI is one of only two therapies approved for Alagille syndrome and progressive familial intrahepatic cholestasis, and it grew about 46% year over year to roughly $128.7 million in Q2 2026. The most optimistic published target, $185.00, assumes this works close to its best case.

The case against. The August 2026 volixibat decision is the clearest illustration of the risk: a Phase 2b study met its primary endpoint and had Breakthrough Therapy designation, and the FDA still recommended a full Phase 3, pushing an NDA to the first half of 2027 and knocking roughly 10% to 15% off the stock in a session. The most pessimistic target, $125.00, is roughly what MIRM is worth if this bites instead.

Read the full bull and bear case on MIRM, including what would have to change to break either one. Walnut is not an investment adviser.

A simple financial snapshot. These are approximations and refresh quarterly; for current figures see Mirum Pharmaceuticals, Inc.'s investor relations page or your broker.

• Net product sales (TTM): ~$618 million, up ~44% year over year
• Q2 2026 product sales: ~$176.2 million, up ~38%, with LIVMARLI ~$128.7 million and bile acid medicines ~$47.5 million
• 2026 guidance: ~$680 million to $700 million, raised from ~$660 million to $680 million
• R&D expense (Q2 2026): ~$90.5 million, against SG&A of ~$81.5 million
• Cash and investments: ~$561.3 million at June 30, 2026, up from ~$391.4 million at year-end 2025
• Market cap and multiple: ~$5.7 billion at ~$94 a share, roughly 9x trailing sales and ~8x guided 2026 sales

Earnings multiples do not work on this name right now. The roughly $726 million in-process R&D charge from the Bluejay acquisition pushed trailing net loss to about $860 million, and the Q2 2026 loss was about $67.2 million, or $(1.06) a diluted share, so investors generally value Mirum on revenue and pipeline probability instead. At roughly 8 to 9 times sales the market is paying a growth-biotech multiple for a business compounding above 40%, which means a meaningful share of the price rests on programs that are not yet approved. Beta runs near 0.5, low for a biotech, because the stock moves on regulatory news rather than with the broad market.

If you want MIRM exposure as part of a larger bundle rather than directly, these ETFs hold it meaningfully. Weights are approximate and refresh quarterly.

Other names that sit close to MIRM: same theme, named as a direct competitor, or held beside it in the same funds. Each entry says which. Worth a look if you are thinking about diversification within a thesis rather than concentration on one ticker.

There are three common ways to get MIRM exposure. Buy shares (or fractional shares) directly at any major broker. Hold an ETF that includes it (XBI), which spreads the position across many companies. Or build it into a focused thematic portfolio, so MIRM sits alongside other stocks that express the same thesis.

Walnut takes the portfolio route. Describe a thesis where MIRM fits (for example “AI infrastructure” or “dividend-growth large-caps”) and the AI proposes 5 to 6 constituents with target weights. You review the plan and fund it through your own broker when you're ready.

New to this? Start with how to invest in stocks, see how to analyze a stock with AI, or compare the best AI stock analyzers.

Mirum pairs a genuinely profitable-scale rare-disease commercial franchise with a pipeline that has repeatedly moved the stock 10% or more in a day, and the two halves rarely get priced at the same time.

Whether MIRM is worth buying today depends more on your time horizon and what you already hold than on any single call. We walk through valuation, what would have to go right, and the risks in is MIRM a buy or a sell?, and where the stock could go from here in the MIRM stock forecast.

For income investors, whether MIRM pays a dividend and how the payout looks is covered in does MIRM pay a dividend? And to weigh MIRM against a peer, read the full side-by-side comparisons: MIRM vs REGN and MIRM vs GILD.