Legal & General yesterday snapped up Cofunds Holdings for £131m from a consortium of City fund managers.
The insurer, which has targeted bolt-on acquisitions under new boss Nigel Wilson, said the deal will help it expand its digital business.
Cofunds is a so-called platform that helps investment advisers and clients manage their portfolios of money.
The deal will boost assets under management in the group's savings division to £103bn.
L&G said it expects to make cost savings of about £11m each year from 2015.
Mark Gregory, the head of savings at the group, said: "The projected growth in the investment platform market is substantial and we expect Cofunds to be a major beneficiary of this growth.
"Our acquisition of Cofunds will create a great opportunity to extend our asset-gathering capability and grow our savings business."
Legal & General already owned 25 per cent of Cofunds alongside asset managers such as Jupiter and Threadneedle.
The company expects to complete a deal by the end of June.