Oil magnate Mukesh Ambani and steel tycoon Lakshmi Mittal made it to the top 10 of the Forbes magazine list of world's richest billionaires.

Ambani ranked fourth with $29 billion and Mittal ranked fifth with $28.7 billion on the Forbes list of billionaires released Wednesday.

The biggest loser in the world this year was Anil Ambani, who lost $32 billion - 76 percent of his fortune - as shares of his Reliance Communications, Reliance Power and Reliance Capital all collapsed, Forbes said on its website. He was last year's biggest gainer.

Ambani is one of 24 Indian billionaires, all but one of whom are poorer than a year ago. Another 29 Indians lost their billionaire status entirely as India's stock market tumbled 44 percent in the past year and the Indian rupee depreciated 18 percent against the dollar, Forbes said.

India is no longer the top spot in Asia for billionaires, ceding that title to China, which has 28.

Mexican telecom tycoon Carlos Slim Helu topped the list, with $53.5 billion, $500 million ahead of long-time list topper Bill Gates, founder of Microsoft. Legendary investor Warren Buffet was third with $47 billion.