Athletes make most of their money from endorsements, and as one of the hottest Olympians around, Phelps will surely find himself inundated with endorsement offers. He already has made millions from a couple of big brands — Under Armour, Speedo, Subway, Hilton, Head and Shoulders, and more. These sponsorship deals have earned him about $5 million to $7 million every year, says Forbes.
And with his latest triumph in London, we're likely to see more of Phelps advertising products. Cha-ching!