Novo Nordisk abruptly ended its partnership with Hims & Hers after the Danish drugmaker accused the telehealth company of illegally selling cheaper copycats of Novo Nordisk’s weight-loss drug and engaging in deceptive marketing.

Novo Nordisk said it's ending its collaboration due to concerns with Hims & Hers the company's sales and promotion of cheap knock-offs of the weight loss drug Wegovy, it said on Monday.

Hims & Hers Health shares tumbled nearly 35% Monday after Novo Nordisk said it is pulling out of its partnership with the digital pharmacy, citing "illegal" and "deceptive" practices.