The successful case brought by the Accountancy and Actuarial Discipline Board (AADB) is the latest sign of how regulators are taking a harder line on auditors, seen by policymakers as being too soft on banks in the run-up to the financial crisis.

The AADB said PwC, one of the world's "Big Four" auditors, which check the books of nearly all blue-chip companies, admitted it failed to obtain "sufficient appropriate evidence" to report that J.P. Morgan Securities complied with strict client money rules spanning several years.

Most of the client money from futures and options trading was being daily "swept" into interest-bearing, unsegregated accounts overnight at J.P. Morgan Chase bank, the firm's parent, said the AADB.

In June 2010 the U.K. Financial Services Authority (FSA) slapped a record 33.32 million pound fine on J.P. Morgan Securities for failing to keep client money separate at all times from the firm's money over a seven-year period to July 2009.