As per latest Forbes rich list, Reliance Industries chairman Mukesh Ambani is ranked 40th globally with net worth of USD 18.6 billion -- the highest for any Indian.
This is his lowest rank for Mukesh Ambani since being placed at 56th position in the year 2006 with a net worth of USD 8.5 billion -- the first year when Mukesh and his younger brother Anil Ambani were ranked separately by Forbes after their split.
The current net worth of USD 18.6 billion of Mukesh Ambani also marks a significant decline from USD 43 billion of wealth recorded in 2008, when he was ranked 5th richest across the world.
It was in the year 2008 itself, when Mukesh Ambani entered the top league of 10 richest people in the world and remained there for four consecutive years till 2011.
"Worth USD 43 billion in 2008 when he was the world's fifth richest person, Mukesh Ambani has seen a precipitous decline in his fortune since then, a USD 2.9 billion drop in the past year alone," Forbes said.
Regardless, Forbes said he remains India's richest person and is "still bullish". Ambani plans to invest USD 25 billion in his businesses over the next two years.
"Ambani has been more in the news for controversies linked to his Reliance Industries' KG-D6 oil field which is set to reap a bonanza from an upcoming gas price hike," Forbes said.
Steel tycoon Lakshmi Mittal has also been witnessing a steep fall over the last 10 years. In the latest Forbes list Mittal is ranked in the 52nd position, while in the year 2005, he enjoyed a rank as high as the 3rd on the global rich list.
Lakshmi Mittal's firm ArcelorMittal is weighed down by weak demand and heavy debt but remains the world's biggest steelmaker.
The company reported a net loss of USD 2.5 billion in 2013, lower than that of the previous year, thanks to cost cutting measures.
According to Forbes, a weak economy and falling rupee took their toll on the wealth of Indian billionaires.
In the 2014 Forbes list, India has 56 billionaires in all with a collective net worth of USD 191.5 billion which is a tad lower than last year's haul of 55 names worth USD 193.6 billion.
Among those with evaporating fortunes are brothers Shashi & Ravi Ruia, this year's biggest dollar losers, down by USD 3.6 billion as shares of their London-listed Essar Energy tumbled.