MBX Third-Quarter Net Loss Widens to $62.4 Million

The Tip Desk · November 12, 2026 · 3 min read

Third-quarter operating expenses rose to $66.3 million; cash, cash equivalents and marketable securities reached $481.6 million, reflecting $97.6 million in net at-the-market stock-sale proceeds.

MBX Biosciences, Inc. (MBX) reported total operating expenses of $66.3 million for the third quarter ended September 30, 2026, compared with $23.9 million a year earlier. Net loss widened to $62.4 million from $21.6 million.

The clinical-stage biopharmaceutical company developing precision peptide therapies for endocrine and metabolic disorders dosed the first patient in August 2026 in its pivotal Phase 3 oPTimize trial of once-weekly canvuparatide for chronic hypoparathyroidism.

The global, randomized, double-blind, placebo-controlled study is expected to enroll about 160 adults. In the prior quarter the company had said the trial was on track to initiate in the third quarter, with sites activated and participants being recruited. The trial builds on Phase 2 Avail results and one-year open-label extension data presented at ENDO 2026.

Chairman and Chief Executive Officer Steve Hoerter said the third quarter marked an important milestone with the start of the pivotal canvuparatide program.

Cash, cash equivalents and marketable securities were $481.6 million as of September 30, 2026, up from $418.6 million at June 30, 2026. The company said the September 30 balance reflected $97.6 million of net proceeds from the sale of common stock under its at-the-market agreement. Based on its current operating plan, MBX expects the combined balance to fund operations into 2029.

Research and development expenses were $32.0 million for the three months ended September 30, 2026, compared with $19.3 million a year earlier. The company attributed the $12.7 million increase to start-up costs for the canvuparatide Phase 3 trial initiated in the third quarter of 2026, ongoing canvuparatide Phase 2 open-label extension work, the MBX 4291 Phase 1 trial, and timing of preclinical and IND-enabling activities on MBX 5765 and MBX 6180.

General and administrative expenses were $34.3 million, versus $4.7 million a year earlier. MBX said the $29.6 million increase was driven by higher personnel-related costs, including $20.8 million of stock-based compensation related to modification of awards for the company’s former chief executive officer, and other personnel costs from expansion of the executive leadership team and general infrastructure.

Net loss was $62.4 million, or $1.29 a share, for the three months ended September 30, 2026, compared with a $21.6 million loss, or $0.63 a share, a year earlier. Weighted-average shares used in the loss-per-share calculation were 48.6 million. Total operating expenses were $66.3 million. Interest and other income, net, was $3.9 million.

On the obesity pipeline, MBX remains on track to report unblinded 12-week multiple ascending dose (Part C, Cohort 1) data for MBX 4291, a GLP-1/GIP co-agonist prodrug designed for once-monthly dosing, in the fourth quarter of 2026. Cohort C1 is evaluating 30 mg once weekly for four weeks, followed by 120 mg and 180 mg once monthly, in adults with a BMI of 30 kg/m2 or higher.

IND-enabling studies continue for MBX 5765, an amycretin prodrug combining GLP-1, GIP, glucagon and dual amylin/calcitonin receptor agonist activity. Preclinical pharmacokinetic data for MBX 6180, a GLP-1/GIP/GCG triple agonist prodrug, were accepted for a poster at ObesityWeek 2026, November 14–17, in Washington, D.C. MBX 6180 was nominated as a development candidate in the second quarter; IND-enabling studies for it are ongoing.

In September 2026 MBX appointed Jeff Held as Chief Legal Officer. In October it appointed Peter Radovich, President and Chief Operating Officer of Mirum Pharmaceuticals, to its Board of Directors.

The company said it remains on track to report the MBX 4291 readout and continues to advance canvuparatide through pivotal development while investing in the obesity portfolio, with cash expected to support operations into 2029.