#Hagens Berman #MoonLake Immunotherapeutics #SLK

MoonLake Immunotherapeutics Faces Class Action Lawsuit

MoonLake Immunotherapeutics, known by its stock symbol MLTX, is currently embroiled in a securities class action that has surfaced following the company's alarming Phase 3 trial outcomes for its sole drug candidate, sonelokimab (SLK). This legal action, titled Bridgewood v. MoonLake Immunotherapeutics, et al., and filed in the Southern District of New York, reflects serious investor concerns regarding the dramatic decline in MoonLake's stock value.

On September 29, 2025, the company announced that the results of its trials for SLK, intended for treating hidradenitis suppurativa (HS), fell far below expectations, leading to a staggering decrease in share price by approximately 90%, erasing $55.75 in market value per share in just one day. Investors were left blindsided as the announcement of the trial's disappointing data followed a series of assurances from MoonLake regarding the efficacy and potential success of SLK.

The crux of the class action revolves around allegations that prior to the release of these unfavorable trial results, MoonLake misrepresented critical information regarding both the clinical trial's design and SLK's effectiveness compared to existing treatments. More specifically, the lawsuit claims that the company misled investors about the expected clinical effectiveness of SLK, particularly in relation to BIMZELX, a competitor that is already FDA-approved and addresses the same condition.

MoonLake had continuously highlighted the supposed advantages of its product, claiming that the Nanobody format of SLK provided superior efficacy over traditional monoclonal antibodies like BIMZELX. They stated that SLK could achieve benefits that