Biovail Corporation saw its share price sink by as much as 10% on the Nasdaq Stock Exchange on Friday after the company revealed that the US Securities and Exchange Commission had launched a formal investigation into its accounting practices.

The SEC launched an informal inquiry back in November 2003 asking for historical financial and related information for all of 2002 and up to November 2003. In a statement, Biovail said that this period has now been extended to June 2001.

The company says that it has been fully co-operating with the SEC, “and will continue to do so, in an effort to bring the investigation to a conclusion as expeditiously as possible.”