Industry observers have been stunned by the news that Lundbeck’s chief executive Ulf Wiinberg has resigned with immediate effect after breaching the Danish company's code of conduct by accepting shares in the UK biotech Stratified Medical.

Mr Wiinberg has quit “at his own request” after omitting to obtain board approval for a gift of 55 shares from the founder of privately-held Stratified in 2013. Lundbeck subsequently invested in the company to the tune of 19 million Danish kroner, about £2 million.

Mr Wiinberg said "I am sincerely sorry for the course of events, which on my part was unintentional”. He stated that “I am proud of having taken part in the development and strengthening of the company. However, based on these events, I have found it in both parties' best interests that I resign”.

Lundbeck chairman Hakan Bjorklund noted that Mr Wiinberg “has not only acknowledged but also apologised for his erroneous actions”. However, he added that “this does not change the fact that Lundbeck has a clear and unmistakable code of conduct for all employees [and] we cannot operate with degrees of compliance”.

Mr Bjorklund, who has head of Nycomed from 1999 to 2011, will serve as interim CEO until a replacement is found.