IBM Corp, Armonk NY, is acquiring Ottawa-based Cognos Inc for US$5 billion, the largest acquisition in IBM's history and the 23rd in its so-called information-on-demand strategy. The deal is the latest development in the rapidly consolidating field of firms in the business intelligence and performance management software sector, following SAP AG's merger with Business Objects SA and Oracle Corp's purchase of Hyperion Solutions Corp. IBM will integrate Cognos into its information software management division and is expected to retain the Cognos brand. Cognos is the last major stand-alone software firm in the Ottawa region and has 4,000 employees worldwide serving more than 25,000 customers. Founded in 1969, it finally cracked the $1-billion sales milestone earlier this year and had just acquired Applix Inc, Westborough MA, for $339 million….