Novo Nordisk (NYSE:NVO) shares have dropped by close to 4% this week, shedding more than £350 billion from its market cap, after a study suggested there may be a link between its blockbuster weight loss drugs Wegovy and Ozempic and vision loss.
Those who have been prescribed the weight-loss injection are at a higher risk of developing an eye condition linked to blindness, the study said.
People with diabetes who take the treatment were around four times more likely to be diagnosed with non-arteritic anterior ischemic optic neuropathy (naion), the research revealed.
Jakob Westh Christensen, analyst at eToro said: "Considering that over 50% of Novo Nordisk (NYSE:NVO)’s sales are attributed to these two blockbuster drugs and with a promising projected growth trajectory, any significant issues with the drugs could pose a threat to earnings and stock prices.
"However, the relatively minor market reaction indicates that investors are not overly concerned about this initial study.
"It is important to note that this study is relatively small and has limited statistical power. The findings do not prove that the medications caused the eye complications, which are commonly associated with diabetes.
"To establish any connection properly, a much larger study must be conducted."