Complex sentence: Keith Thurman Jr. (born November 23,1988) is an American professional boxer who has held the WBA welterweight title since 2013 (promoted to Super champion in February 2017) and the WBC welterweight title since March 2017.
Split into simpler sentences: Keith Thurman Jr. (born November 23,1988) is an American professional boxer. He is currently a unified welterweight champion, having held the WBA welterweight title since 2013 (promoted to Super champion in February 2017) and the WBC welterweight title since March 2017.