Sister Mary Jean Ryan will step down as president of SSM Health Care starting Monday. Ryan, 73, will become chair of the hospital system's board of directors. She has been the company's CEO since its founding in 1986. William Thompson, 60, will follow Ryan as the company's new CEO. SSM, which is based in St. Louis, owns 15 hospitals and two nursing homes in Missouri, Illinois, Wisconsin, and Oklahoma. There are seven SSM hospitals in the St. Louis region. "The word inspiring gets thrown around a lot, but in Sister's case, there is no other word for the example of her bold leadership," Thompson said in a statement. Thompson has worked for SSM for 31 years, and became COO in 2009.