Shares in the world’s biggest insulin maker, Novo Nordisk, closed down almost 2% after falling as much as 3% during very heavy trading on December 2, as US regulators slammed a safety warning on the label of its anti-bleeding drug NovoSeven (recombinant Factor VIIa).

The Danish group said the FDA action follows the results of a study released earlier this year, which showed an increase in the risk of blood clotting in patients who do not suffer from haemophilia.

The shareholders’ initial knee-jerk reaction to the news is likely down to the fact that NovoSeven is considered the group’s main growth driver outside of its diabetes medicines. But the general feeling among analysts is that sales of the drug won’t see any dramatic impact, as the data behind the warning has been in the public domain since February.