Shares in Rightmove, Britain's biggest property website, jumped nearly 20 per cent yesterday as investors rushed to buy into the hotly pursued IPO on its London stock market debut.

By 8:17 a.m. British time, the stock had fallen back from initial highs but was still trading up about 13 per cent from the 335p issue price. At the session peak of 396-3/4 pence, Rightmove had a market capitalisation of over £500 million.

The listing price was at the top end of a 275-335p price range set by the company during its roadshow, a range which had to be increased midway through the flotation process because of strong interest.

Rightmove declined to say how much demand there was for the IPO. Traders reported speculation that there were requests for 35 times more shares than the 22.7 million on offer.

"It was a very popular IPO. The book was well covered," a spokesman for Rightmove said.

Dealers and analysts have also said in recent weeks that interest in Rightmove was helped by a favourable valuation compared with UK property adviser Savills.

The high demand echoed the IPO of Lastminute.com six years ago - Britain's most hyped internet flotation at the time although shares in the online retailer fell below their issue price soon after listing.

Less than a fifth of Rightmove's share capital was sold in the IPO and existing investors such as Countrywide, HBOS and Connells Ltd, part of the Skipton Group, all retained stakes of slightly more than 20 per cent each in the company. Royal & Sun Alliance still holds about five per cent of Rightmove.

Swiss bank UBS was the sole sponsor and bookrunner for the IPO, while British broker Panmure Gordon was the co-lead manager.