Partnership Assurance prices float at 385p a share A total of £485m has been raised, of which £125m which will go to pay down debt at the insurer. It is selling 93,528,185 existing shares and 32,467,532 new shares, representing a free float of around 31pc. At a market value of £1.5bn, Partnership is eligible for inclusion in the FTSE 250 Index. Conditional dealings - or so-called grey market trading - have started, with the shares rising 20pc to 460.5p. Unconditional trading is due to begin on June 12. About 90pc of the group's revenues come from selling "non-standard annuities" (NSAs) to retirees suffering from medical conditions such as diabetes, cancer or multiple sclerosis. The rest is from customers with an average age of 87, who are going into care homes. The company says its database, built up over close to two decades, enables it to estimate accurately a customer's expected reduction in life expectancy, allowing it to offer better annuity rates than rivals. An ageing population and the switch from final salary to defined contribution pension schemes have both increased the demand for annuities, according to the company. Partnership's market is also growing because, according to independent research, only 32pc of people currently purchase NSAs when 55pc-65pc could be eligible. The insurer, which has 26pc of the non-standard annuities market, saw operating profits rise 42pc last year to £112m, when new business premiums rose 42pc to £1.26bn. Operating profits have grown 56pc since 2010. Consultants Oliver Wyman believe the NSA market has been growing at a compound 33pc between 2006 and 2012, with the market forecast to grow from £4.5bn to £8.1bn by 2016. Partnership is chaired by former London Stock Exchange chairman Chris Gibson-Smith.