MUMBAI: Businessman Anil Ambani , who a little over a decade ago was one of the richest persons in the world with a net worth of about $42 billion, may not be a billionaire any more. At Tuesday’s close of trading on Dalal Street , the combined market capitalisation of all of Anil Ambani-controlled Reliance Group companies was nearly Rs 5,400 crore, or about $773 million.Ambani holds less than 75% stake in each of the six companies in his group — Reliance Infrastructure, Reliance Naval & Engineering, Reliance Power, Reliance Capital , Reliance Home Finance and the now-defunct Reliance Communications . Going by the market value of listed companies in his group, the younger of the two famous Ambani brothers would be worth much less than the billion-dollar mark.Till recently, the group had a large stake in a profitable mutual fund business — Reliance Nippon Life Assets Management — a joint venture with Japanese life insurance major Nippon Life, which has been sold to its partner recently. Currently valued at nearly Rs 13,500 crore, or a little over $2 billion, the fund house is in the process of being transferred to the Japanese insurance major.Anil, the younger brother of Mukesh who is listed as the 13th richest man in the world with a net worth of $50 billion by Forbes, has been going through several challenges in almost all his businesses.At one point of time, Anil held over 60% in Reliance Communications, the telecom venture which is currently going through the bankruptcy process under the Insolvency and Bankruptcy Code, with its total debt at nearly Rs 58,000 crore. Auditors have resigned from three of his companies — Reliance Capital, Reliance Home Finance and Reliance Infrastructure — after alleging non-cooperation and wrongdoings on the part of their management. The group is fighting these allegations by the auditors.The holding company for all of the group’s defence businesses, Reliance Naval & Engineering, has been in the red for several quarters. And so is the power-generation business, Reliance Power, which in 2008 had one of the most hyped IPOs in Indian stock market history.A look at Anil’s depleting wealth shows that after peaking at $42 billion in 2008, he has been steadily losing net worth, with the global financial crisis months during late 2008 and early 2009 being the most savage when he saw over 75% vanish. By mid-2009, his net worth was down to about $10 billion. From then on, it’s been a steady slide for him.Interestingly, in 2008 when Anil was ranked sixth among the world’s richest, Mukesh, with a net worth of $43 billion, was at the fifth position. Currently, Mukesh’s net worth is about $51 billion. Forbes’ real-time net worth indicator, however, shows Anil’s net worth at $1.5 billion. This indicator considers a person’s total wealth that includes all the stakes he/she holds in listed companies as well as in unlisted companies and other assets.