COPENHAGEN (Reuters) -Drugmaker Novo Nordisk said on Monday it would halt its Wegovy weight-loss drug agreement with U.S. telehealth company Hims & Hers Health, pushing Hims shares down 31% in morning trading.

Novo Nordisk’s new weight-loss drug helped patients lose even more weight on average than its current Wegovy blockbuster treatment, an early-stage trial showed, as the drugmaker races to develop the next generation of obesity medicines.

Some new medications in development are also trying to solve for a persistent side effect of existing drugs: Patients who lose fat also tend to lose muscle. This can be particularly dangerous for older adults because it makes them more likely to fall and can worsen osteoporosis.