Twelve years ago, when their audit of Enron's last accounts heralded the demise of Arthur Andersen, the largest end of the audit market shrank to four firms.

The Competition Commission (CC) has now provisionally concluded that the audit market is restricted: companies are inhibited from switching auditors and there is a tendency for auditors to focus on satisfying the needs of management rather than shareholders. The Commission is mandated by the OFT to consider what, if anything, should be done about it.