George Herbert Walker III, a cousin of two presidents, a former United States ambassador to Hungary and a prominent St. Louis businessman and philanthropist, died on Saturday at a hospice facility in St. Louis. He was 88.

His son, George, said on Thursday that the cause was complications of a stroke that Mr. Walker had about a year ago.

Mr. Walker grew up in Greenwich, Conn., and graduated from the Groton School in Massachusetts before earning a bachelor’s degree from Yale University in 1953 and a law degree from Harvard in 1955.

After serving two years in the Air Force, he moved to St. Louis in 1958 to work for a financial services company founded by George Herbert Walker, the grandfather he shared with his first cousin, George H.W. Bush, who also grew up in Greenwich. Mr. Walker was later president and chief executive of the business, Stifel, Nicolaus & Company, which grew significantly under his watch and which he took public in 1982.