Shares of Zealand Pharma plunged more than 30%, marking the company’s worst trading day on record, after new clinical data for its experimental obesity drug failed to meet investor expectations.

The sharp selloff erased about 8.3 billion Danish crowns, or roughly $1.3 billion, from the company’s market capitalization during early trading in Copenhagen.

Trial Results Disappoint Investors

The experimental therapy, petrelintide, helped patients lose up to 10.7% of their body weight over 42 weeks in a mid-stage clinical trial involving 493 participants.

While the results demonstrated meaningful weight reduction, investors had expected stronger outcomes given the intense competition in the rapidly growing obesity treatment market.

The drug is being developed in partnership with Roche as part of a collaboration announced in 2025 aimed at expanding both companies’ presence in metabolic disease therapies.

Competition Raising the Bar

The obesity drug market has become one of the most competitive areas in the pharmaceutical industry.

A rival amylin-based drug candidate from Eli Lilly delivered weight loss of up to 20.1% in a comparable mid-stage trial, setting a higher benchmark for efficacy.

The race to develop highly effective weight-loss medications has accelerated as pharmaceutical companies compete for a share of a market expected to generate tens of billions of dollars annually.

Recent Pressure Across the Sector

The disappointing data from Zealand Pharma follows a recent setback for Novo Nordisk, whose shares declined after its next-generation obesity drug underperformed a competing treatment from Eli Lilly in a head-to-head study.

These developments highlight the growing pressure on pharmaceutical companies to demonstrate superior results as new therapies enter development.

Analysts See Potential but Not Market Leadership

Some analysts believe petrelintide could still play a role in obesity treatment, though its positioning may be limited.

Research notes suggest the therapy may show promising tolerability and could potentially be used in weight-loss maintenance programs rather than as a first-line treatment.

However, analysts indicated that the latest data could make it difficult for the drug to compete directly with leading therapies currently dominating the market.