They have lost more than $13 billion from their combined wealth, but still the two Ambani brothers have moved higher on Forbes' latest list of the world's ten richest CEOs, while Sunil Mittal has joined the league and Lakshmi Mittal has slipped two places.

Legendary American investor Warren Buffett has retained his top position on the annual list, but Indian-born steel tycoon Lakshmi Mittal has been toppled from his last year's second position by software major Oracle chief Larry Ellison.

Mittal has moved down to fourth position, while Mukesh Ambani, the elder of the two warring brothers, has jumped three positions to grab third rank this year.

The younger Ambani, Anil, has also moved up one place to sixth rank on this year's 'Forbes list of ten wealthiest CEOs'.

While another Indian business chief, Azim Premji, has moved out of the top-ten list, compatriot Sunil Mittal of Bharti Airtel [Get Quote] has joined the league at ninth position.

IT major Wipro [Get Quote] Chairman Premji was ranked ninth on the previous year's list. The total number of Indians on the list has remained unchanged at four on this year's list.

"Being a CEO isn't what it used to be. Crackdowns on corporate frills like private jets and over-the-top offices have become the norm, taking some of the fun -- but none of the stress -- out of running billion-dollar businesses," Forbes said.

"While some chief executives' jobs may be in peril, these 10 have stuck it out long enough to partake in what's left of the global economy. These have made our annual list of the world's wealthiest CEOs," it added.

About India's presence on the list, Forbes said there are four Indians on its list this year: "two industrialists, Mukesh Ambani and Lakshmi Mittal; and two telecom tycoons, Anil Ambani and Sunil Mittal."

"(The) Ambani brothers owe their hefty fortunes, in part, to inheritance. Following their father's death in 2002, they took over his industrial empire . . . and attempted to run it together.

"The collaboration soon soured. After coming to blows over who ran the company, the two reached a bitter compromise, deciding that they and the company would best be served by spinning off and divvying up its various businesses.

"Today Mukesh runs petrochemicals giant Reliance Industries Ltd [Get Quote], while Anil oversees an array of companies including Reliance Communications [Get Quote], a phone and Internet outfit with 60 million customers," it added.

The magazine said that its list of the world's wealthiest CEOs was based on analysis of their financial stakes in firms controlled by them, as on January 23.

Buffett has been ranked first with $35.9 billion worth of shareholding, it said, adding that "there are not many people who can lose $25 billion in four months and still top the list of the world's wealthiest CEOs."

Oracle's Ellison has been ranked second with $19.7 billion, followed by Mukesh Ambani ($16.8 billion), Lakshmi Mittal ($13.2 billion), luxury goods major LVMH's Bernard Arnault ($12.2 billion), Anil Ambani ($nine billion), Arabian bank Mashreq's Abdul Aziz Al Ghurair ($7 billion), and Microsoft's Steve Ballmer ($7 billion).

Sunil Mittal ($6.9 billion) and Japanese fashion retail major Fast Retailing's Tadashi Yanai ($6 billion) follow.

"We estimated ownership by sifting through each company's most recent financial filings and, where information was not readily available, talking to industry sources," Forbes said, adding that both CEOs and managing directors of public companies across the world were considered for the list.

About Mukesh Ambani, the report said he made it to third position despite a 62 per cent plunge in the shares of his group's flagship firm RIL since January last year.

On Lakshmi Mittal, it said that the 58-year-old has consistently ranked among the top five wealthiest people in the world, but his public holdings of ArcelorMittal took a dive in the second half of 2008, falling 73 per cent since June.

About Anil Ambani, the report said that "in the four years since a spat with older brother Mukesh led to the break-up of their family's assets, Anil, the younger of the two, has grown his telecom, energy and infrastructure businesses apace--only to see his shares decimated by the global economic slowdown."