The Financial Services Authority (FSA) is investigating a jump in the share price of Biffa, the waste management group, that occurred before an announcement that two private equity firms had made a £1.2 billion bid for the company. According to the Times the FSA is believed to have written to various parties involved in the talks to ask what they knew about any potential bid approach before a statement from HgCapital and Montagu Private Equity in November that they had submitted a takeover proposal. A FSA spokeswoman said: There is not a lot we can say we do not confirm or deny the reports. We do not comment specifically on a particular company. If a share price moves up or down by an awful lot without no reasonable explanation then our market monitoring team looks into it. Moves in share prices are usually made on the back of a company making an announcement but when there is no reasonable explanation for it then we would look into it. Looking into share prices happens reasonably regularly and is not an unusual occurrence. The FSA investigation will put pressure on Montagu and HgCapital as they proceed with due diligence on Biffa, having been given access to the companys books after raising their bid by 20 pence to 350 pence on December 7 and promising to pay the dividend. A Biffa spokesman said that the FSA is conducting routine market monitoring investigations.