Shares in Krispy Kreme plunged nearly 13% yesterday on high volume trading, but the US doughnut maker and retailer said it did not know the reason behind the unusual stock trading activity.

"Although as a matter of policy the company does not comment on unusual market activity or rumours, the company stated that it is unaware of what has triggered the unusually high trading volume and decline in its stock price today," Krispy Kreme said.

Shares in Krispy Kreme, which sells premium doughnuts in the US, Australia, Canada, Mexico, South Korea and the UK, have fallen since the company warned on profits in May 2004, reported Reuters. The company is facing investigations from the US Securities and Exchange Commission and was recently sued by its Southern California franchisee.