Tesco Shares Are Getting Punished

Tesco shares are down 8% Monday morning after Britain's biggest supermarket chain revealed that it overstated its profit outlook in the first half of the year by £250 million ($408 million).

According to Tesco, the error was "caused by an early booking of revenue and delayed recognition of costs," Reuters reports. The accounting issue was "discovered during preparation for its forthcoming interim results."

Newly-appointed leader Dave Lewis said on a call that four executives have been asked to step down, including Chris Bush, the head of Tesco operations in the UK, Bloomberg News reports.

"Tesco's U.K. executives were obviously under pressure to be seen to be making progress," Bryan Roberts, an analyst at Kantar Retail, told Bloomberg News. "This is pretty catastrophic for them and will probably mean some senior people will have to go."

Tesco has a current market cap of £17 billion.