The stock fell 31 percent on the Copenhagen Stock Exchange.
In a Phase 2 study for the company's drug candidate petrelintide, an average weight loss of 10.7 percent was achieved after 42 weeks.
The result was lower than expected. Analyst firm Jefferies had expected a weight loss of 13–15 percent.
"Petrelintide has the potential to redefine weight management. These results bring us closer to the goal of giving people obesity treatments that fit the lives they actually want to live," the pharmaceutical company said in a press release.
The company plans to proceed with Phase 3 studies later this year.
Zealand Pharma is developing the drug together with Swiss pharmaceutical company Roche, whose shares fell 3 percent.
