Novo Nordisk A/S’s best-sellers Ozempic and Wegovy transformed the firm into a global pharmaceutical giant. But four years after Wegovy’s US launch, the Danish drugmaker’s growth is slowing. About one million patients in the US are taking cheaper copycat options.

Shares in Novo Nordisk fell as much as 6% on Friday to their lowest since August 2021, extending recent losses to wipe out almost all the gains made since the drugmaker launched its blockbuster weight-loss treatment Wegovy.