Big Four deny acting against shareholders The Commission, in a report detailing the findings of a landmark investigation into Big Four dominance, claimed that in many instances, auditors and company executives have acted as a cabal to their mutual benefit, and to the exclusion of the interests of investors. The firms, which audit nearly all big businesses in the UK and worldwide, and have often served the same client for decades, also voiced opposition to a controversial proposal to force Britain's listed companies to switch accountants periodically. "Arbitrary pre-set periods will potentially damage audit quality, and forced rotation will undermine audit committees and actually reduce shareholder choice," warned Simon Collins, chairman of KPMG's UK arm. David Barnes, managing partner at Deloitte UK said: "Although we understand why mandatory tendering and rotation have been raised as potential remedies that may help the perception of competition, we are concerned that the importance of continuing to increase audit quality risks being ignored in this debate."