This Biotech Fund Just Dumped $14.8 Million in MBX Biosciences — Right Before Key 2026 Milestones

On November 14, MPM BioImpact disclosed in a Securities and Exchange Commission filing that it sold out its entire stake in MBX Biosciences (NASDAQ:MBX), reducing exposure by an estimated $14.8 million.

What Happened

According to a filing with the Securities and Exchange Commission dated November 14, MPM BioImpact sold its entire position in MBX Biosciences during the third quarter. The fund exited 1,294,416 shares, eliminating its exposure and reducing reportable U.S. equity holdings by an estimated $14.8 million based on quarterly average pricing.

What Else to Know

Top holdings after the filing:

• NASDAQ:MDGL: $46.1 million (7.5% of AUM)
• NASDAQ:CGEM: $45.4 million (7.4% of AUM)
• NASDAQ:RNA: $33.1 million (5.4% of AUM)
• NASDAQ:TRVI: $31.2 million (5.1% of AUM)
• NASDAQ:EWTX: $27.9 million (4.6% of AUM)

As of last Wednesday's market close, MBX shares were priced at $33.82, up 71% over the past year and well outperforming the S&P 500, which is up 13% in the same period.

Company Overview

Company Snapshot

MBX Biosciences develops precision peptide therapies targeting endocrine and metabolic disorders, with lead candidates including MBX 2109 for chronic hypoparathyroidism, MBX 1416 for post-bariatric hypoglycemia, and MBX 4291 for obesity and related conditions. The company operates a clinical-stage biopharmaceutical business model, generating value through research, development, and potential future commercialization or licensing of proprietary drug candidates. Primary customers are expected to include healthcare providers, endocrinologists, and specialty clinics treating metabolic and endocrine disorders, with an eventual focus on patients requiring long-acting hormone therapies.

Foolish Take

MBX has been one of the more volatile names in the biotech space, plunging roughly 75% from its September 2024 IPO through this March before rebounding sharply on strengthening clinical data and renewed investor interest. The stock now trades above its IPO price, reflecting a very different risk profile than it had just months ago.

According to the latest SEC filing, MPM sold all its stake in MBX—nearly 1.3 million shares—during the third quarter, an estimated $14.8 million reduction in a name that previously represented a meaningful allocation. The firm also exited MoonLake Immunotherapeutics and Crinetics Pharmaceuticals during the same period, signaling broader repositioning across its emerging-biotech exposure.

For its part, MBX continues to advance its pipeline: In the third quarter, the company reported positive topline Phase 2 results for canvuparatide in hypoparathyroidism, completed a $200 million upsized offering, and ended the quarter with $391.7 million in cash, which the firm says is enough to fund operations into 2029. CEO Kent Hawryluk highlighted the momentum, noting, “These strong results support our belief that canvuparatide has the potential to be best-in-class in hypoparathyroidism, an estimated multibillion-dollar market.” He also emphasized the drug's upcoming Phase 3 initiation and key 2026 milestones. For long-term investors, the message is clear: MBX is accelerating toward multiple pivotal catalysts, but its path remains highly data-dependent.

Glossary

13F reportable assets: Assets disclosed by institutional investment managers in quarterly SEC Form 13F filings, showing U.S. equity holdings.

Assets under management (AUM): The total market value of investments managed by a fund or investment firm.

Exposure: The amount of capital or percentage of a portfolio invested in a particular asset or sector.

Net position change: The difference in the value or number of shares held in a security after a trade or series of trades.

Clinical-stage biopharmaceutical: A company focused on developing drugs that are being tested in human clinical trials but are not yet approved for sale.

Prodrug technology: A drug design approach where an inactive compound is converted into an active drug within the body.

Precision peptide therapies: Targeted treatments using short chains of amino acids (peptides) designed for specific biological effects.

Phase 2: The second stage of clinical trials, assessing a drug’s effectiveness and side effects in patients.

Preclinical: Research and testing of a drug candidate in the laboratory or in animals before human trials begin.

Licensing: Granting rights to another company to develop, manufacture, or sell a product, often in exchange for fees or royalties.

Endocrine disorders: Medical conditions involving hormone-producing glands, affecting metabolism, growth, or other body functions.

TTM: The 12-month period ending with the most recent quarterly report.

Jonathan Ponciano has no position in any of the stocks mentioned. The Motley Fool recommends Cullinan Therapeutics. The Motley Fool has a disclosure policy.