Phelps signed his first-ever endorsement deal with Speedo in 2001 when he was 16 and had extended the deal for four years in 2009. He's swimming in his first meet since the 2012 Olympics.
Visa, which has sponsored Phelps since 2002, said the swimmer's success at Beijing raised his visibility and would make possible a global.
Phelps's deal with Under Armour
Another of Phelp's huge sponsors is Under Armour. Although the exact size of the deal has not been disclosed, a report by The Street suggests that Phelps earned US$5 million from the endorsement.