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.

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 Inc.’s stock closed down 4.8% Tuesday, after the company said a mid-stage trial of its weight-loss treatment MariTide showed up to 20% average weight loss at 52 weeks. Analysts were expecting the treatment to achieve an average weight loss of about 20% to 25% after one year,