Advertising titan WPP's interest in buying Tesco's data arm Dunnhumby is by logic, a compelling opportunity, said brokerage firm Bernstein.The broker on Wednesday reacted to WPP's confirmation of interest in Tesco's data business on Tuesday when WPP boss Sir Martin Sorrell spoke at the Media & Telecoms conference in London.In his speech Sorrell said he was interested in the business behind the supermarket's Clubcard loyalty scheme which was put up for sale in January by Tesco.Tesco picked Goldman Sachs in January to explore options for Dunnhumby as part of the widespread cost cutting and downsizing of Tesco under chief executive Dave Lewis. As such, suitors have eyed up the data business with WPP and private equity firms touted as the likely candidates.WPP however made the first move by confirming its bid for the customer data company, which would give the advertising giant access to data that helps conglomerates such as Kellogg's and Coca-Cola set prices and promotions."We think WPP would be a great buyer for the asset and we also think Dunnhumby is a very attractive business (high cash, high growth, significant barriers to entry in its core businesses), more valuable than recent press reports would have it and therefore a potential positive catalyst for Tesco in the near future," said Bernstein.For Tesco, selling Dunnhumby will strengthen the balance sheet and enable it to focus on the core, said Bernstein. It added that selling Dunnhumby for £2 billion or more will be "an excellent start in deleveraging the business while at the same time increasing the focus on turning around the core of the business."For WPP, Bernstein said the logic of the deal is compelling, but execution could pose some challenges, however acquiring Dunnhumby from a strategic point of view is positive as "adding additional repositories of large data can only enhance further this competitive position."Bernstein rates WPP and Tesco both at 'outperform' with a target price of 1950p and 285p, respectively.