Brokers reduce wholesaler rolls; Recent Aon move favors two firms, one of them Ryan's.(Company overview)

Byline: MICHAEL BRADFORD

Aon Corp. has limited the number of wholesalers it uses to just two under most circumstances, continuing a trend among retailers to streamline their distribution networks.

And while many of Aon's peers have made such moves--though few as drastic--questions remain about whether restricting wholesale markets helps or harms insurance buyers.

Aon last month decided that all new and renewal business that requires a wholesaler would be first submitted to AmWINS Group Inc. or R-T Specialty L.L.C. Only if neither can provide coverage or "when the circumstances of the placement require involvement of a different wholesaler, will another wholesaler be approached," Aon said in an emailed statement.

AmWINS, based in Charlotte, N.C., was ranked the No. 1 wholesale broker by Business Insurance last year, based on $3.72 billion in 2009 premium volume. R-T Specialty is a wholesale brokerage unit of Chicago-based Ryan Specialty Group L.L.C., the holding company formed last year by Patrick G. Ryan, Aon's founder and former chief executive.

Aon, which at one time was willing to deal with more than 100 wholesalers, declined to discuss its decision, but a spokesman emphasized in a statement that the broker believes the move is a good one for its clients.

"Significant changes to the …