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.

Amgen said its experimental weight loss injection helped patients lose up to 20% of their weight on average after a year, with no plateau, in a critical mid-stage trial. But shares of Amgen fell on Tuesday,