IBM Corp, moving to strengthen its future in network computing, says it will buy the remaining 30% of the Advantis data network services business from partner Sears, Roebuck & Co for $450m. IBM currently owns 70% of the business that the two companies formed in 1992 to provide network, data processing and value-added telecommunications services to US-based customers. IBM says that the purchase reflects the company’s belief that network computing will become increasingly significant to its revenues. The sale will allow Sears to focus more on its core retailing business.