AXA is understood to have bought Smart & Cook in a deal thought to be worth £170m.
Although neither company would comment, market sources said senior staff at the Harrogate-based broker had been told of the sale. Other senior insurance executives also said that the deal had been agreed.
The purchase, the third broker acquisition by AXA this year, is likely to have major ramifications in the insurance industry, prompting rival insurers to consider their distribution channels and strategies.
Rumours had been circulating for some time that AXA was looking to buy Smart & Cook, which was number 27 in Insurance Times Top 50 UK Brokers list.