The Ambani brothers famously split after their father Dhirubhai's death in 2002 sparked a feud that led to a division of the family business empire in 2005.
Mukesh got energy-based conglomerate Reliance Industries, the crown jewel, while Anil got Reliance Comm and the infrastructure and power businesses.
Dhirubhai Ambani was himself a legendary figure who rose from an impoverished village in Gujarat to found Reliance, a company that at one point accounted for 15 percent of India's exports.
The brothers' dispute came to a head over terms of a gas contract, which raged on even as they lived under the same roof with their mother and families, captivating India in a real-life soap opera.
In 2009, Anil attacked his brother and the oil minister in a series of newspaper ads, accusing the petroleum ministry of siding with publicity shy Mukesh.
The Supreme Court ultimately intervened and decided in Mukesh's favour. The 2010 ruling brought the brothers back to the negotiating table, where they unexpectedly agreed to scrap the non-competition pact that had been a source of conflict.
That prompted speculation, still unfulfilled, that they will work together again.