4D Molecular Therapeutics FDMT Shares Surge 6.30% on Positive CF Gene Therapy Data, Insider Buys

4D Molecular Therapeutics (FDMT) shares reached their highest level since this month on Dec. 18, surging 6.30% intraday as positive clinical data and insider confidence bolstered investor sentiment. The stock, which has risen 6.27% over two days, reflects renewed optimism in the biotech’s gene therapy pipeline.

The rally followed the release of interim Phase 1 AEROW trial data for 4D-710, a variant-agnostic gene therapy for cystic fibrosis (CF). The results showed durable CFTR protein expression and improvements in lung function metrics like ppFEV1 and LCI2.5, with no new safety concerns in higher-dose cohorts.

These findings reinforced the therapy’s potential as a one-time, long-lasting treatment for CF, a condition with high unmet needs. Earlier volatility, including a 15% drop on Dec. 1 over moderate initial data, was tempered by the latest update, which supported advancing to Phase 2 trials.

Insider activity also influenced perceptions. Director Charles Theuer’s Dec. 12 purchase of 9,333 shares signaled confidence in the company’s near-term trajectory, while Officer Scott Bizily’s Dec. 16 sale of restricted shares under a prearranged plan was deemed routine. The CF market, targeting 40,000 U.S. patients, offers significant commercial potential, with 4D-710’s orphan and rare pediatric designations potentially accelerating regulatory pathways. Meanwhile, the company’s 4D-150 candidate for wet AMD and DME, in Phase 3 development, could diversify revenue streams.

Investors remain focused on upcoming milestones, including Phase 2 enrollment completion for 4D-710 by H1 2026 and a program update by year-end. The $100 million 2025 financing round underscores financial readiness, though capital efficiency will remain critical. With a strong unmet need in CF and a robust pipeline, FDMT’s stock appears poised for continued interest as clinical and regulatory progress unfolds.