The ABI said its investment activities, including the Institutional Voting Information Service, will operate in conjunction with the IMA following the merger.
Discussions between the two are currently in their final stages, and the new organisation's name and chairman are yet to be chosen.
The ABI said the new group would give both organisations a “single, stronger and more coherent voice”.
Despite this change, the ABI will continue to represent insurers as asset owners.
The IMA is a representative body for the UK investment management industry, with members managing over £4.5trn of assets on behalf of UK and overseas clients. Its board consists of senior members of the industry who publish and commission research into various technical projects
Formed in 1986, the ABI provides consumers with general information on insurance and savings products and services. It has almost 300 member companies, accounting for 90% of the UK insurance market. In 2012, its members were responsible for £1.8trn in investments, 25% of the UK’s total net worth.