Members of the Portman building society have been told that they will receive a bonus payment, should a merger with Nationwide get the go ahead. About 1.2 million Portman members stand to receive a bonus of between �200 and �1,000.
Portman members will vote on whether to approve the merger at the society's AGM on 23 April.
Nationwide is currently the UK's largest building society, while Portman is the third-biggest.