Wal-Mart named former American Airlines CEO and Chairman Tom Horton as a member of its board Monday. Horton, 53, ascended to the top job at American Airlines Group Inc. in 2011 and he stepped down late last year after the carrier merged with US Airways. Horton is also a former chief financial officer of American Airlines and of AT&T Inc. Wal-Mart Stores Inc. has 15 other board members. The company is based in Bentonville, Arkansas, and it has more than 11,000 stores in 27 countries.