Quilter has sold its heritage life and pensions devision, Old Mutual Wealth Life Assurance Ltd, to ReAssure for £425m.
Quilter said the sale, which had an "attractive valuation", would solidify its position as an advice-led and modern wealth manager.
Quilter Life Assurance, a closed book of unit-linked policies, was once the core of Quilter's UK business. It was made up of pensions, investment and savings and protections products, with both retail and institutional offerings.
Quilter said it expects the growth profile of the firm to grow as a result of the sale because the life assurance business was in "run-off". It said the sale would allow it to increase its focus on the delivery of its growth strategy and "the execution of its optimisation initiatives".
Quilter CEO Paul Feeney said: "ReAssure is a highly regarded manager of closed book assets and has the experience to deliver continued high quality investment and administration services to clients of Quilter Life Assurance.
"The Quilter board is currently minded to return a meaningful proportion of the net surplus proceeds arising from the transaction to shareholders and will consult with them on the most appropriate means of undertaking this."
Combined five decades’ experience
Following Zurich acquisition
Bannister oversaw Standard Life acquisition
Firm's third acquisition this year