CHICAGO--(BUSINESS WIRE)--Grant Thornton LLP announced that Stephen Chipman, senior vice chairman of Grant Thornton LLP, has elected to retire early from the firm in order to pursue new opportunities in line with his professional ambitions, effective October 31, 2015. “Stephen has demonstrated incredible stewardship, leadership and friendship during his tenure,” said J. Michael McGuire, Grant Thornton’s chief executive officer. “He has taken our firm to new heights during some of the most chall