After its merger with ICIS, Threadneedle has moved up from sixth place to fourth with 55 clients. At the start of last year it had only 30.
FD stayed at the top with 80 clients, while Pelham Bell Pottinger beat Buchanan Communications into second place with 63 and 61 clients respectively.
Pelham Bell Pottinger topped the table by aggregate stock market capitalisations of clients, while Buchanan and FD shared top spot for FTSE AIM 100 clients.
Abchurch Communications and College Hill share fifth spot in the overall rankings, while Tavistock Communications gained three additional clients to climb to seventh.