Amgen's experimental drug MariTide helped overweight or obese patients shed up to 20% of their body weight in a mid-stage trial, but the results failed to meet lofty investor expectations and shares of the biotech company tumbled about 12% on Tuesday.

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 Inc. shares fell the most in 23 years after its experimental obesity shot failed to significantly outperform rivals and showed a high rate of gastrointestinal side effects.The reaction shows how high the bar is for new weight-loss drugs.