 Founded by former Boston Consulting Group associate Walker Lewis in 1981, Strategic Planning Associates applied concepts of computing to strategy consulting.Unlike many of his peers, Lewis had never gone to business school, opting instead to start his own firm building computerized models for clients such as Ameritech Corporation (which would later become AT&T), Chase Bank, General Electric, and Royal Dutch Shell.By 1986, the consultancy was worth $25 million in 1990 US dollars, but just two clients accounted for more than 40% of their revenue.