Anil Ambani slipped to number 34 on the list, from number six last year
Indian businessman Anil Ambani has been revealed as the biggest loser on the 2009 Forbes World Billionaire list, losing $31.9bn over the past 12 months.
Mr Ambani, who runs the telecoms and finance arms of the former Reliance Group, had been 2008's biggest gainer.
India's billionaires saw massive falls, with Mr Ambani's brother Mukesh and steel tycoon Lakshmi Mittal both seeing over half their net worth wiped out.
The 793 people listed lost 23% of total wealth on average over the past year.
The impact of the global economic downturn on people's fortunes was apparent, with 332 names from last year's list not making the cut.
Anil Ambani's losses saw him drop to number 34 on the list, from number six last year.
Mukesh Ambani, who heads Reliance Industries, saw his fortune shrink from $43bn last year to $19.5bn.
However, despite slipping two places to number seven on the list, he overtook Lakshmi Mittal, boss of steelmaker Arcelor Mittal, as India's richest man.
Mr Mittal's wealth has plummeted from $45bn to $19.3bn, according to Forbes. He fell from number four to number eight on the list.