Is MIRM a Buy or a Sell? The Bull and Bear Case (2026)

That depends on which case you find more convincing, and both are on this page. The bull case rests on LIVMARLI compounding in two approved indications, with net product sales (ttm) at ~$618 million, up ~44% year over year. The bear case rests on 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. Analysts covering it are spread from $125.00 to $185.00, which is itself a signal that this is genuinely contested. If you believe the thesis, the real questions become sizing and overlap rather than timing. Walnut is not an investment adviser and this is not a recommendation.

Nobody can answer that for you, and the honest version of the question is narrower: has anything changed in the reason you bought it? The bear case on this page is the place to check. 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. If that risk is what you were worried about and it is now playing out, that is a real signal. If the price simply fell while the thesis held, that is a different situation entirely. The most pessimistic published target is $125.00, +32.8% from the $94.11 price, which is one analyst's downside case rather than a floor. Walnut is not an investment adviser.

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 analyst target on MIRM is $185.00, +96.6% from the $94.11 price. That figure is only reachable if this thesis works close to its best case.

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. The most pessimistic published target is $125.00, +32.8% from the current price, which is roughly what the stock is worth if these risks bite rather than the drivers.

Mirum Pharmaceuticals sells three approved medicines for rare liver and bile-acid diseases, led by LIVMARLI, alongside a mid-stage clinical pipeline.

Decide that in advance, because it is far harder to think clearly once a position is moving against you. The concrete tripwires here: the driver behind the bull case (LIVMARLI compounding in two approved indications) stalling in the reported numbers rather than in the narrative, the risk above (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) turning from a possibility into a reported fact, or the position growing large enough that a bad outcome would matter to your whole portfolio regardless of who is right.

Three approved medicines for rare diseases. LIVMARLI (maralixibat) treats Alagille syndrome and progressive familial intrahepatic cholestasis and produced about $128.7 million in Q2 2026. CHOLBAM (cholic acid) treats bile-acid synthesis disorders, and CTEXLI (chenodiol) is the only FDA-approved therapy for cerebrotendinous xanthomatosis in adults. Those two are reported together and added about $47.5 million in the quarter. Total trailing revenue is roughly $618 million.

Alongside Q2 results on August 5, 2026, Mirum disclosed that the FDA recommended a Phase 3 study of volixibat in primary sclerosing cholangitis, even though the VISTAS Phase 2b trial met its primary endpoint and the drug holds Breakthrough Therapy and Orphan Drug designations. The filing moved to the first half of 2027. Shares fell roughly 10% to 15% to about $94 despite a revenue beat and raised guidance.

Not on a reported basis. The company posted a net loss of about $67.2 million in Q2 2026, or $(1.06) a diluted share, and trailing net loss screens near $860 million because of a roughly $726 million in-process R&D charge tied to the Bluejay Therapeutics acquisition in the first quarter. Product sales are growing above 40% and cash rose to about $561.3 million by June 2026, so the underlying commercial business and the reported loss tell different stories.