MIRM · Mirum Pharmaceuticals

The thesis

Mirum Pharmaceuticals is modestly more likely than not to lead the S&P 500 over three months. Both Phase 3 hepatitis delta studies of brelovitug are now positive, and LIVMARLI sales are growing. The fourth-quarter 2026 report, expected around 25 February 2027, tests the $715–720 million sales guide and should give the first Atebrioz sales figure.

Mirum announced on 10 November 2026 that AZURE-4 met its primary endpoint at week 24: 59% of patients on weekly brelovitug and 44% on monthly dosing reached the combined virologic response and liver-enzyme (ALT) normalisation endpoint, against 0% on delayed treatment, in 113 treatment-naïve patients (Mirum press release, as summarised by Panabee). With AZURE-1 reported on 28 September 2026, the biologics license application (BLA) package is complete, and Mirum plans to file in the first half of 2027.

The shares closed at $93.18 on 9 November 2026 and $94.42 on 10 November 2026, the day of the announcement. The result moved the price little. The last close of $93.33 on 12 November 2026 is 28.2% below the 52-week intraday high of $130.00 on 9 July 2026 and 7.3% lower over three months.

Bullish and bearish views on Mirum Pharmaceuticals, Inc.

The bull case on Mirum Pharmaceuticals, Inc. (MIRM), in brief: second Phase 3 win completes the filing package. The bear case: costs are growing faster than sales.

Bull case

• Second Phase 3 win completes the filing package. AZURE-4 hit its primary endpoint with a p-value of 0.0001 or lower and no new safety signals, with flu-like illness the most common adverse event at about 17–19% (Panabee summary of the 10 November 2026 release). AZURE-1's Phase 3 portion showed 56% and 45% responses against none on delayed treatment on 28 September 2026.
• Hepatitis delta responses deepen with time. HCPLive reported on 8 November 2026 that HDV RNA fell below the limit of quantification in 80% of weekly-dosed Phase 2b patients at week 48, up from 45% at week 24, and in 40% of monthly-dosed patients, up from 10%.
• Sales and guidance both moved up. Third-quarter 2026 net product sales were $185.7 million, up from $133.0 million a year earlier. LIVMARLI was $133.4 million, up 45%, and bile acid medicines were $52.3 million, up 28%. Mirum raised its 2026 guide to $715–720 million from $680–700 million (8-K, 3 November 2026).
• Approvals and filings are lined up. The FDA approved Atebrioz (zilurgisertib) for fibrodysplasia ossificans progressiva (FOP) on 25 September 2026, and LIVMARLI's EXPAND study met its primary endpoint on 12 October 2026. Mirum plans a brelovitug BLA, a LIVMARLI supplement and a volixibat filing in the first half of 2027.
• Analyst targets rose after the data. Citigroup kept a Buy rating and raised its target to $194 on 11 November 2026, per a news report. Citizens raised its target to $167 from $144 on 4 November 2026, per MarketBeat.

Bear case

• Costs are growing faster than sales. Third-quarter research and development was $107.9 million against $43.0 million a year earlier, and selling, general and administrative expense was $88.9 million against $61.9 million. The result swung to a $59.7 million operating loss from $2.6 million of operating income (8-K, 3 November 2026).
• Cash is falling while debt has grown. Cash and investments were $500.5 million on 30 September 2026, down from $561.3 million on 30 June 2026, and a $25.0 million Atebrioz approval milestone went to Incyte in October. Net convertible notes were $731.3 million, with 6,826,045 shares issuable on conversion against 65,282,044 outstanding on 30 October 2026 (10-Q, 3 November 2026).
• The shares did not react to the readout. The close moved from $93.18 on 9 November 2026 to $94.42 on 10 November 2026, and the 200-day average of $98.45 remains above the last close of $93.33.
• Atebrioz has no reported sales yet. The third-quarter release gave no Atebrioz figure, so the first read comes with fourth-quarter results. It enters a market where Ipsen's Sohonos was approved in August 2023.
• Insider selling and a target cut followed the Q3 report. CEO Christopher Peetz sold 20,000 shares at $90.00 on 4 November 2026 under a Rule 10b5-1 plan, leaving 206,637 shares (SEC Form 4). Leerink Partners cut its target to $140 from $154 on 5 November 2026, per MarketBeat.

Price setup

The shares closed at $93.33 on 12 November 2026. That is above the 50-day average of $88.92 and below the 200-day average of $98.45, both from adjusted daily closes. The three-month change is –7.3% from the $100.64 close of 14 August 2026.

The 52-week intraday high is $130.00 on 9 July 2026, and the 52-week closing low is $64.10 on 15 December 2025. Closes between 5 November 2026 and 12 November 2026 ranged from $93.18 to $94.61, a narrow band across the third-quarter report, a medical-meeting presentation and the AZURE-4 result.

Supply comes from planned insider sales near $90 to $100 since August and from the convertible notes. The next scheduled financial report is the fourth-quarter 2026 results, which Mirum has not yet dated.

Catalysts ahead

• ~25 February 2027 (est.): Fourth-quarter 2026 financial results, date not announced and estimated from the prior-year report. Tests the $715–720 million sales guide and should show the first Atebrioz sales figure.
• ~31 March 2027 (est.): Volixibat VANTAGE Phase 2b topline in primary biliary cholangitis, guided for the first quarter of 2027. Shows whether volixibat can reach a second liver indication beyond the planned primary sclerosing cholangitis filing.
• ~30 June 2027 (est.): Brelovitug BLA, LIVMARLI EXPAND supplement and volixibat submissions, planned for the first half of 2027. Turns the 2026 trial results into regulatory filings and possible approval dates; Mirum targets a U.S. brelovitug launch in the fourth quarter of 2027 if approved.

What would change the view

A daily close below $75, which would show the market rejecting two positive Phase 3 hepatitis delta results and a raised sales guide. A cut to the $715–720 million 2026 net product sales guide would also end the case.

The risks this note tracks, each with what would confirm it:

• Operating expenses keep outgrowing sales and raise the need for capital. Confirmed by: fourth-quarter 2026 research and development and SG&A above the third quarter's $107.9 million and $88.9 million with sales near the low end of the $715–720 million guide, or a convertible or share offering.
• Atebrioz launches slowly in a small FOP market that already has an approved therapy. Confirmed by: fourth-quarter 2026 results showing minimal Atebrioz revenue, or management commentary on a small treated population.
• The brelovitug filing slips or the FDA asks for more data. Confirmed by: a BLA not submitted by the end of the first half of 2027, or an FDA request for additional studies.
• Competing hepatitis delta treatments narrow brelovitug's commercial opening. Confirmed by: a competitor approval or new head-to-head data in hepatitis delta, for example from Gilead or Vir Biotechnology.
• Analyst targets drift down as spending estimates rise. Confirmed by: more target cuts or downgrades following Leerink's cut to $140 from $154 on 5 November 2026.

What it trades with

The shares trade mainly on Mirum's own trial readouts, approvals and quarterly sales, which places them among event-driven commercial rare-disease biotechs. The link to Incyte is contractual: Mirum licenses Atebrioz from Incyte and owes mid-to-high single-digit royalties plus milestones, per the third-quarter 10-Q. LIVMARLI and the bile acid medicines treat rare cholestatic liver diseases, so sales follow patient adoption more than the economic cycle.