Pwc, Deloitte, KPMG and EY sign off the accounts of 97% of the UK's 350 largest listed companies.
MPs have said the stranglehold of the big four accountancy firms on the audit market needs to be broken.
Business and Work and Pensions Committees. say the competition regulator should look at breaking them up to prevent another situation like Carillion which collapsed months after accountants KPMG signed off its books.
But what impact might such a massive shake up have?
What have MPs proposed?
The committees want the government to refer the accountancy market to the competition regulator to investigate two possibilities. The first is breaking up KPMG, Deloitte, EY and PwC into smaller companies.
The second possibility is that the big four “detach” the audit part of the business which checks companies' books, from consultancy part that offers advice.
The committees say this is needed because there is an inherent conflict of interest in having the two under one roof.
An auditing firm has an incentive to not highlight problems at a firm it is extracting juicy consultancy fees from. Non-audit work now makes up £4 in every £5 of fees for the big four.
Why have MPs proposed this?
The committees put forward the first, more radical, proposition because they say there is not enough competition in the audit market. The four firms sign off the accounts of 97 per cent of the UK's 350 largest listed companies.
Firms over a certain size have to be audited and the largest of those companies have little choice but to employ one of the big four accountants to carry it out. No other accountancy firms have the manpower and other resources to be able to do the job.
This often results in “cozy” relationships like the one between Carillion and KPMG, which had audited the collapsed construction firm’s accounts for 19 years and failed to highlight serious problems.
What would happen if they are split up into smaller firms?
One possibility is that two or more smaller accountancy firms jointly audit large companies. France has this system and it has helped maintain a more competitive market than in the UK. The accountants produce a joint audit report and cross-check each others work, potentially making it more reliable. Both firms are then liable for the contents of the report.
Andrew Oury, partner at law and accounting firm Oury Clark says there "is some truth that ‘size matters’ but the cosy relationship needs disrupting”.
“Part of the solution could be an independent appointment from a wider pool of auditors for public interest entities – however those are defined.”
What would happen if audit and consultancy departments were split?
Accountancy firms would need to think of a new business model. Lower-level staff at the big four firms currently carry out a large volume of audit work. The job is inherently boring but the bargain is that new recruits slog their way through and eventually work their way up to more interesting and lucrative work. They also get their fees paid for professional exams.
If audit had to be hived off into a separate company the job would arguably be less attractive to talented graduates. However, it would at least mean that the employees carrying out audits are doing so because they want to rather than as a stepping stone to something else.
The most obvious positive is that auditors would clearly be working for shareholders of companies they audit, not the managers of those companies. This is, of course, the role that auditors are supposed to have been playing all along.
Is this a good idea?
It certainly has a lot of support. The Carillion disaster is merely a particularly high-profile example among many cases of auditors apparently failing in their duties. Apart from the two committees of MPs, the head of the accountancy watchdog, the Financial Reporting Council, also said recently it was time to break up the big four.
Sacha Romanovitch, the chief executive of the fifth-largest accountancy, Grant Thornton, has called for the CMA needs to investigate the sector. His firm stopped bidding to audit FTSE 350 companies recently, saying it was too expensive to do so.