Growth within the top end of the independent broking market is at its lowest rate since 1999, Cornell Consulting warned.
Cornell's annual review of the top 250 independent brokers' distribution rates showed growth plummeted to 9% in 2004.
But the top ten independent brokers increased their income by 28%.
Acquisitions in the top end of the market also soared, with 18 businesses being acquired or joining a network. But, Cornell said most acquisitions at this level had been carried out by Willis.
The review found the top 250 broking networks now control 65% of the sector, up from 57% last year.
Cornell estimated that about 20% of brokers at the lower end of the sector had quit the market because of FSA compliance costs.
Cornell Consulting chief executive Tony Cornell said brokers were seeing a downturn in the sector. He warned independent brokers to "put into place tactics so they can ride out the downturn".