NEW YORK ( TheStreet) -- Bill Gates and Warren Buffett are no longer the world's richest men. Carlos Slim Helu, who owns telecom holdings including American Movil ( AMX), is now No. 1, according to the 2010 Forbes list of the world's billionaires. The Mexican mobile tycoon's fortune has risen to an estimated $53.5 billion, up $18.5 billion in 12 months, Forbes says. Gates, chairman and co-founder of Microsoft ( MSFT), with a fortune valued at $53 billion, ranked second in the world. Gates held the title as the world's richest 14 of the past 15 years. Buffett ranks third as his fortune increased $10 billion to $47 billion on rising shares of his investment vehicle Berkshire Hathaway ( BRK-B). His $5 billion investment in Goldman Sachs ( GS) played a part in his boosting his fortune. -- Written by Joseph Woelfel in New York. >>>Also see: Carlos Slim Helu's Holdings Follow TheStreet.com on Twitter and become a fan on Facebook.