MIRM · Mirum Pharmaceuticals, Inc. · Stock research

Current Thesis

The commercial base did what it was supposed to. On 2026-08-05 Mirum reported Q2 net product sales of $176.2M against a $166.1M consensus, LIVMARLI at $128.7M (+46% YoY) and bile-acid medicines at $47.5M (+20% YoY), and raised the FY2026 net-product-sales guide a second time — to $680–700M from $660–680M, against a $675.2M consensus. The tape ignored it. The 2026-08-14 close of $100.64 sits 21.7% below the $128.57 52-week high, and the three-month return of -1.5% means the entire June–July breakout leg has been given back. Two things changed the story: volixibat's PBC topline moved to Q1 2027 with the NDA now targeted H1 2027 (previously an H2 2026 filing), removing one of the three 2H26 binaries the June narrative was built on; and four brokers cut targets on 2026-08-06 after six raises between 2026-06-11 and 2026-07-07. What remains is a pre-PDUFA event bet resting on the June shelf near $100–105, with the zilurgisertib FOP decision dated 2026-09-26 and AZURE-1 Phase 3 topline guided into Q3 2026.

Bullish and bearish views on Mirum Pharmaceuticals, Inc.

The model's bull view on Mirum Pharmaceuticals, Inc. (MIRM), in brief: Guidance raised twice in one year. FY2026 net product sales to $680–700M on 2026-08-05, from the $660–680M set on 2026-05-06 and against a $675.2M consensus. The raise came with the revenue beat, not instead of it. The base franchise is compounding, not plateauing. Q2 LIVMARLI… The bear view: A binary was removed, not resolved. Volixibat VANTAGE PBC topline slipped to Q1 2027 and the NDA to H1 2027. The June-July thesis priced three 2H26 events; one is now a 2027 event. The bottom line missed despite the top-line beat. GAAP net loss $67.2M, $(1.06) per share; the… Both cases follow in full.

Bull Case

• Guidance raised twice in one year. FY2026 net product sales to $680–700M on 2026-08-05, from the $660–680M set on 2026-05-06 and against a $675.2M consensus. The raise came with the revenue beat, not instead of it.
• The base franchise is compounding, not plateauing. Q2 LIVMARLI $128.7M, +46% YoY; bile-acid medicines $47.5M, +20% YoY; total product sales $176.2M.
• Zilurgisertib FOP data remains the strongest card. PROGRESS pivotal Phase 2 (ENDO 2026, 2026-06-14) reported a 99.9% reduction in new heterotopic-ossification lesion volume. The NDA holds Priority Review with a PDUFA target action date of 2026-09-26 in patients 12 and older; FOP affects roughly 300 U.S. and 900 worldwide patients, so pricing power is orphan-grade and competition is minimal.
• Three readouts inside two quarters. AZURE-1 Phase 3 HDV 24-week topline guided Q3 2026, AZURE-4 Q4 2026, LIVMARLI EXPAND Phase 3 Q4 2026 — all stated on the 2026-08-05 call.
• Balance sheet funds the calendar. Cash, equivalents and investments of $561.3M at 2026-06-30 ($330.7M cash, $107.6M short-term, $123.0M long-term investments).
• Published targets sit far above the tape. Even after the 2026-08-06 cuts, the band is $135–$140 (RBC $135, Citizens $137, TD Cowen $140, HC Wainwright $140) versus a $100.64 close on 2026-08-14.

Bear Case

• A binary was removed, not resolved. Volixibat VANTAGE PBC topline slipped to Q1 2027 and the NDA to H1 2027. The June-July thesis priced three 2H26 events; one is now a 2027 event.
• The bottom line missed despite the top-line beat. GAAP net loss $67.2M, $(1.06) per share; the adjusted figure reported at $(0.80) against a $(0.68) consensus. Q2 R&D was $90.5M and SG&A $81.5M against $176.2M of product sales.
• Sell-side round-tripped in eight weeks. Six raises 2026-06-11 → 2026-07-07 (MS $150, RBC $148, Citizens $146, JPM $125, HC Wainwright $185 among them), then four cuts on 2026-08-06 — RBC $148→$135, Citizens $146→$137, HC Wainwright to $140, TD Cowen to $140.
• A raised guide produced a lower price. That is the observable that dates the narrative's life-cycle: on 2026-08-05 the company beat and raised, and by 2026-08-14 the stock was at $100.64.
• FOP economics are shared with Incyte, the licensor of zilurgisertib, so an approval on 2026-09-26 splits its P&L contribution.
• Prior-quarter accounting distortion persists in comparisons. The Bluejay acquisition drove a $726.3M in-process R&D charge and a $790.2M Q1 net loss, $(13.43) per share.

Setup & Price Structure

Reference close 2026-08-14: $100.64. That is 21.7% below the $128.57 52-week high and RSI(14) reads 34.9 — weak, but not a washed-out extreme. The three-month return of -1.5% is the cleanest description of what happened: a full round trip through the June breakout and back.

The structure that matters is the June shelf near $100–105, which price is now sitting directly on rather than above. The prior published frame treated a hold of that shelf as the condition for the momentum leg; that condition is being tested in real time, not comfortably satisfied.

The narrative is saturated. Dating it — coverage is mainstream and fully priced (five-plus banks with published targets), the raise-then-cut cycle completed between 2026-06-11 and 2026-08-06, and the 2026-08-05 beat-and-raise failed to produce a bid. New attention is not arriving; the incremental buyer of the June story has already bought.

Crowding and positioning observables, stated without a verdict: the $135–$140 target band sits 34–39% above the 2026-08-14 close, a wide price-versus-coverage divergence; four target cuts landed in a single session on 2026-08-06; 2026-07-13 inducement grants carried a $122.13 strike, now well above the current tape; early-July Form 4s showed routine 10b5-1 sales (CEO ~20k shares, CFO ~5k) with no offsetting open-market insider buying disclosed since. No new filings have appeared in the window since the Q2 release.

Catalyst Calendar (next 30 days)

• ~2026-09-30 (est.), guided "Q3 2026" — AZURE-1 Phase 3 24-week topline in chronic hepatitis delta. Guided on the 2026-08-05 call; undated, so it can print inside the next 30 days without warning.
• 2026-09-26 — zilurgisertib FOP PDUFA target action date. 41 days from 2026-08-16, so just outside the 30-day window, but it is the fixed date the whole calendar is organised around.
• ~2026-11-05 (est.) — Q3 2026 results. First test of the raised $680–700M guide.
• ~2026-12-31 (est.), guided "Q4 2026" — AZURE-4 Phase 3 topline and LIVMARLI EXPAND Phase 3 topline.
• ~2027-03-31 (est.), guided "Q1 2027" — volixibat VANTAGE Phase 2b PBC topline, with NDA submission targeted H1 2027.

What Would Change Our Mind

The June shelf near $100–105 is the last defined structure under price, and it is being tested at the 2026-08-14 close of $100.64. A weekly close below $100 removes it and leaves nothing technical between the tape and the 2026-09-26 decision — at that point the name is a pure regulatory coin-flip with a broken chart, which is a different instrument from the one the June narrative described.

Three other things would flip the read. A zilurgisertib CRL, or an approval narrowed below the NDA's 12-and-older population, on or around 2026-09-26. An AZURE-1 Phase 3 topline in Q3 2026 that fails the 24-week combined virologic-response and ALT-normalization primary. Or a further schedule slip — any move of AZURE-4 or EXPAND out of Q4 2026 at the Q3 call would make the volixibat delay a pattern rather than one asset's timing.

What would rebuild the constructive case: a weekly close reclaiming the $114–115 area last seen on 2026-07-22, or an approval plus a positive AZURE-1 topline landing inside the same quarter, which would give the sell-side a reason to reverse the 2026-08-06 cuts.

Correlation Notes

• Incyte (INCY) licensed zilurgisertib to Mirum for worldwide development and commercialization. The 2026-09-26 PDUFA outcome reads across to both names in the same direction; INCY's reaction on the day is an independent read on how the market scores the approval.
• HDV competitive read-across runs to Gilead's bulevirtide programme and Vir Biotechnology's tobevibart/elebsiran combination. AZURE-1 and AZURE-4 topline data will be scored against that comparator set, not in isolation.
• IBAT/cholestatic read-across: Ipsen's Bylvay is the direct competitor to LIVMARLI in PFIC and Alagille syndrome; European and U.S. share commentary from either side informs the $680–700M guide.
• Index beta: the name trades with small- and mid-cap biotech (XBI-type exposure) and is rate-sensitive between events, but inside a PDUFA or Phase 3 readout window idiosyncratic risk dominates index flow.