BIG FOUR rivals KPMG and PwC have dominated the listed audit market over the last decade, according to the 2015 corporate adviser ranking guide.

Over the last ten years, KPMG has ousted PwC from top spot by way of client numbers, though PwC remains by far and away the most successful auditor when judged by the aggregate market-cap of its clients. Deloitte and EY retained their respective standings over the ten-year period, but with greatly reduced client counts.

The news that KPMG has been the most prolific plc auditor over the last decade – growing its total stock market clients to 412 from 354 – comes as accounting watchdog the FRC announced plans to investigate KPMG’s work as auditors of failed bank HBOS. In the same period, PwC, EY and Deloitte saw their share of listed clients shrink.

PwC remains the top FTSE 100 auditor in terms of number of clients and total market cap – a position it has held for the entire period – followed by KPMG, Deloitte and EY.

“Perhaps somewhat predictably, the running order at the head of the FTSE 100 remains unchanged from 10 years ago PwC, KPMG, Deloitte and EY continue to dominate the FTSE top-tier, although both Grant Thornton and BDO have subsequently entered the fray – a possible pointer to the shape of things to come,” the report said.

However, the report predicted that ten years from now, the Big Four’s stranglehold on the FTSE’s blue-ribbon clients “may not be quite so tight” if recent changes to UK and European audit regulations, aimed at disrupting auditor-client relationships, achieve the desired effect.

Among smaller auditors, noteworthy performances were attributable to both UHY Hacker Young and PKF Littlejohn – formerly CLB Littlejohn Fraser – Mazars and Jeffreys Henry; all of which made impressive gains and headway up the rankings. Crowe Clark Whitehill (CCW), formerly Horwarth Clark Whitehill, also recorded strong net gains in the period under review. Since 2005, the auditor has more than doubled the number of constituents it represents, enabling it to surge up the rankings.