These billionaires had a better year than any other American ten-figure titans, thanks to surging stocks and skyrocketing valuations of private companies raising funds. Only one person, Amazon’s CEO Jeff Bezos, ranks among both top dollar and percentage gainers–no small feat for a man as wealthy as he is. Bezos, who yesterday offered to send Donald Trump into space, is now the fourth-richest person on Earth, up from number 15 in March, taking the spot of Mexico’s Carlos Slim Helu, who was the world’s biggest dollar loser this year, down $14.2 billion. Runner-up to Bezos: Mark Zuckerberg, whose net worth increased by a relatively more modest $11 billion.