The FSA has widened the scope of its investigation into the near-collapse of Royal Bank of Scotland to include the takeover of US bank Charter One in 2004.
According to The Guardian, the regulator is in talks with major investors in RBS as well as other experts about the fundraising exercises used by the bank during the takeover.
The FSA is expected to publish a report into the collapse in RBS by the end of this year. The regulator had initially said it did not intend to publish the report, which was concluded in December 2010, on why the bank needed a £45bn rescue by the taxpayer in 2008.
In addition to this report, the FSA is also expected to publish another on how it regulated the bank.
The Charter One deal was controversial at the time because it required shareholders to pay to £2.5bn of the £6bn takeover, a move which subsequently put the brakes on further deals.
The report says that major investors are being asked about fundraisings between April 2004 and April 2008, before the October 2008 taxpayer bailout. It was initially thought that the FSA was looking back as far as 2005.