Isaac Rubin, the managing director and founder, said Policy Portfolio was raising the money to strengthen its capital base and eliminate debt.
Mr Rubin's family is selling pounds 1m to pounds 1.5m of shares but will retain a stake of about 60 per cent. Policy Portfolio is expected to have a market value of just over pounds 10m.
The company and its rivals aim to offer insurance policyholders a better price for their savings contracts than they would receive by surrendering them before maturity.
Buyers of such policies have made very good returns. But some fear future prospects are less good as investment returns fall and insurers come under pressure to pay better surrender values.
Founded in 1988, Policy Portfolio made pre-tax profits of pounds 820,000 in the year to end-March, up from pounds 630,000 the previous year and pounds 250,000 in 1990-91. Last year's turnover was pounds 8m, up from pounds 4.6m.
Charterhouse Tilney, the company's broker, has recruited Sir Stephen Waley-Cohen as Policy Portfolio's chairman.