Grant Thornton UK retains its position as the auditor with most AIM clients despite impressive gains from rival BDO in the past year, according to the Morningstar Professional Services Rankings Guide.
The latest rankings show a worrying trend of firms losing an average of 15 clients in the past four years.
In the past quarter, Grant Thornton lost three clients and has 175 overall, ahead of second placed BDO which gained 24 clients to 144.
Crowe Clark Whitehill, placed ninth on the list, has had the largest gain over four years with 29 new clients. The firm has grown its AIM client base for the past six quarters.
PwC leads the AIM 100 with 21 clients, while PwC and Deloitte audit the most AIM 50 clients with 11 each.