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.

Shares of Novo Nordisk (NYSE: NVO) are tumbling on Monday, down 5.6% as of 2:11 p.m. ET. The drop comes as the S&P 500 (SNPINDEX: ^GSPC) and the Nasdaq Composite (NASDAQINDEX: ^IXIC) both jumped 0.7%.