The purchase of the US price-comparison website, Experian’s biggest deal since 1998, sent shares in GUS up 8½p to 992p.

PriceGrabber operates in a market that is growing at 40 per cent a year. Its acquisition will boost Experian’s interactive division, which offers online services such as credit checking and mortgage comparison to consumers. The division will now account for more than 20 per cent of Experian, whose core operation is to offer marketing and information services to businesses.

Don Roberts, Experian’s chief executive, said that PriceGrabber had synergies with his company’s marketing services division, which also has many retail clients. “We increasingly want consumers to think of Experian when they have something important to do in their lives,” he said.

Mr Roberts plans to expand PriceGrabber’s operations, particularly in the UK and Canada.

The deal provides an early Christmas present for the 30 private owners of PriceGrabbers, who include friends and family of the website’s founders. The company’s management team will stay on with Experian.

Analysts said that Experian had a strong record of driving synergies from new acquisitions.One said: “While this deal might seem strange as well as expensive at first sight this has been the case with a number of Experian deals in the past. These have since generated good returns.”

Experian has acquired nine businesses this year, which have helped it to increase profits by 36 per cent.

Mr Roberts said that the pace of acquisitions was likely to slow next year but that organic growth still accounted for 19 per cent of Experian’s growth, which was “pretty healthy”.

GUS, which spun off its majority stake in Burberry Group, the fashion retailer, on Tuesday, also intends to separate Experian from its retail division, which owns both the Argos and Homebase chains. However, a demerger is not expected until late next year at the earliest.

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