The Big Four accountancy firms could lose millions of pounds in fees because of legislation introduced by the Sarbanes-Oxley Act in the US, according to research from BDO Stoy Hayward.

It is estimated that the Big Four may lose £660m (€1bn) in earnings from UK businesses that are listed in the US, based on their most-recently published accounts. PricewaterhouseCoopers (PwC) has £370m at risk, followed by KPMG with £123m.