An IT integration challenge is looming at Yorkshire Building Society, following its takeover of rival Chelsea Building Society.\nYorkshire, which uses SAP BusinessObjects business intelligence software and an Oracle data warehouse, is the larger party in the merger. Its headquarters in Bradford will become the new group\u2019s main office for 135 branches.\nChelsea, which has 35 branches but a comparatively large mortgage book for its scale, instead uses the Unisys Business Information Server for business intelligence. At its headquarters in Cheltenham, it uses the Unisys Enterprise Database Server and Unisys e-commerce software, Microsoft SQL Server and Microsoft Access databases, and runs Microsoft Windows Server 2003 on Dell PowerEdge servers.\nNeither party was able to give details on IT plans. The merger of the two societies is aimed at creating a large rival to the UK\u2019s biggest society, the Nationwide, and will create a society with 2.7 million members, some 178 branches and a mortgage book of \u00a325 billion.\nMore detail is expected in April when the merger is planned tocomplete. But a spokesperson at Chelsea Building Society said that when the merger is finalised the group \u201cwill look at overlapping functions, because we wouldn\u2019t want two IT systems doing the same thing, for example\u201d.