Aon has forged an affinity partnership with a new internet site which is set to increase competition in the 17 million-strong insurance market for those aged 50-plus.

Fifthmoon.com, launched on Monday, will initially offer a range of Aon-brokered motor, roadside assistance and travel products before branching out to household from January 1. It will challenge the dominance of leading insurance providers for the mature market – Saga and Age Concern.

In addition, the website will provide a range of services from online share dealing, travel services and white goods to information on lifestyle, finance and campaign issues relevant to the older generation.

Simon Clegg, a co-founder of Fifthmoon.com, said it had selected the 50-plus market because it was one of the most active users of the internet for information and ecommerce purposes.

Peter Friend, chairman and managing director of Aon's affinity insurance services division, said Fifthmoon.com would enable the giant broker to target the 50-plus age group more effectively. He said: "Fifthmoon's strategy and aspirations are entirely compatible with our own and we are therefore pleased to be working with them on an exclusive basis."

Aon spokesman Tony Martin added that the 50-plus age group was attractive to insurers because they offered a lower risk than younger drivers and householders.

He said that Aon had a track record of targeting this age group after arranging insurance services to Age Concern members.

Research published by Fifthmoon reveals the 50-plus age group holds 40% of the total buying power in the economy – worth £145bn a year and holds 60% of all UK savings and investments.