Steven Anthony Ballmer (/ˈbɔːlmər/; born March 24, 1956) is an American businessman and investor who was the chief executive officer of Microsoft from January 13, 2000, to February 4, 2014, and is the current owner of the Los Angeles Clippers of the National Basketball Association (NBA). As of October 2019[update], his personal wealth is estimated at US $51.9 billion, ranking him the 16th richest person in the world. Ballmer was hired by Bill Gates at Microsoft in 1980 and subsequently left the MBA program at Stanford University. He eventually became President in 1998, and replaced Gates as CEO in 2000. On February 4, 2014, Ballmer retired as CEO and resigned from the Board of Directors on August 19, 2014 to prepare for teaching a new class. On May 29, 2014, Ballmer placed a bid of $2 billion to purchase the NBA's Los Angeles Clippers after NBA commissioner Adam Silver forced Donald Sterling to sell the team. He became the Clippers owner on August 12, 2014; Microsoft co-founder Paul Allen was a fellow owner in the NBA, having owned the Portland Trail Blazers since 1988. His time as Microsoft CEO was controversial, with the company tripling sales and doubling of profits, but losing its market dominance and missing out on 21st-century technology trends. During his tenure, he was widely criticized as the worst CEO in America.