The pharmaceutical manufacturer Amgen announced on Tuesday that an experimental obesity drug helped patients lose up to 20 percent of their weight in a year. The drug, MariTide, is given by injection once a month, compared with once a week for other obesity drugs like Wegovy and Zepbound that are already on the market.

Shares in Amgen fell by double digits Tuesday on results for the company’s MariTide shot, which is viewed as a potential rival to Wegovy and Zepbound.

Amgen's experimental weight loss injection, MariTide, showed up to 20% weight loss in patients without diabetes and 17% in those with diabetes after a year in a phase 2 trial. Despite higher discontinuation rates compared to other drugs,

With Amgen’s MariTide results at the lower end of investors’ expectation of 20% to 25% weight loss, the much-anticipated readout sent the company’s shares tumbling.

Amgen's experimental drug MariTide led to an average weight loss of up to 20% in a year-long mid-stage trial of nearly 600 people who were overweight or obese, the company said on Tuesday.

The pharmaceutical company's MariTide treatment performed well in a Phase 2 study but not as well as Wall Street expected.