AIM, which was launched in 1995, is an investment market that provides opportunities and challenges in equal measure and the same is true for its auditors. In contrast to the FTSE 350, where less than 3% of companies are audited by a non-Big Four firm, the AIM 100 group of companies are audited by 11 different audit firms. The Big Four maintain a significant presence in this index, followed by BDO and Grant Thornton. In addition, RSM, Crowe Clark Whitehill, Jeffreys Henry, Kreston Reeves and UHY Hacker Young all hold audit clients in this market.

Between them, PwC, KPMG, Deloitte, BDO, Grant Thornton and EY account for 92 of the AIM 100 audits, with cumulative fees of some £19.6m. The remaining firms bring in £560,000 in audit fees, equivalent to 2.8% of the market. Although smaller firms do play in this space, the AIM 100 is still heavily skewed in favour of what one could call the ‘Big Four plus Two’. As with the FTSE 350, PwC accounts for the bulk of audit fees, with £8.04m equivalent to 40% of the total market share, albeit down from £9.81m (49% share) in the previous year.

The remaining Big Four together account for £9.2m of the market (46%), up from £7.52m in the previous year. KPMG is ranked number two with audit revenue of £4.09m (up from £3.4m previous year), followed by Deloitte at £2.6m (£2m) and EY at £2.50m (£2.1m). Grant Thornton earns £1.23m (£981,000) in audit fees followed by BDO at £1.12m (£998,000).

For more on this, read Accountancy’s first AIM Auditor Survey 2017 feature here.