The softening market hit the UK's top 250 brokers in 2004 where growth slowed to 9%, Cornell Consulting said.
In its annual review of distribution in the UK commercial market, Cornell Consulting estimated the booming number of acquisitions in the commercial market had urged growth forward.
It said 18 businesses in the top 250 had joined through acquisition or signing up to a network.
For independent brokers, however, it was the lowest growth year since 1999.
The top ten independents increased income by 28% and now have 16% of the market controlled by independents.
The top 250 including networks now control 65% of the market, up from 57% last year. It said networks and their members now control over £800m of the market.
