India’s stock market made its biggest single-day gain of 893 points on Nov. 14, fuelled in large part by companies that were once members of the Reliance Group. If only the Ambani brothers, Mukesh and Anil, had managed to keep together the empire their father built, their combined value today would’ve made them the world’s richest business group. Instead, a bitter fraternal feud continues, fueled by an energy deal gone sour. 

Dhirubhai Ambani, the brothers’ father, had prospered in an India where bureaucrats micromanaged the private sector. Navigating and manipulating the system was a way Indian industrialists built their monopolies. Ambani’s critics even allege that his entrepreneurial talent lay in creating obstacles for his rivals. But Ambani had the vision to see India as an economic superpower long before the economic reforms of 1991 made such dreams possible, and built a business empire to an international scale, making his business globally competitive.

Within two decades Ambani expanded a textile trading company into a textbook example of competitive strategy built on vertical integration: absorb costs and slack, build on economies of scale. By integrating his business backward from textiles to yarn and filament to petrochemicals to refinery, Ambani created an integrated chain of business that was the envy of rivals. For many investors, Reliance had become the proxy for a burgeoning Indian economy.

After Dhirubhai’s passing in 2002, his sons, Mukesh and Anil fell apart. Mukesh was considered the studious one, interested in technology; Anil, the flamboyant one, was fascinated by finance and by new businesses—he graduated from Wharton, where today he remains one of its overseers.

When the businesses split in 2005, Mukesh inherited Reliance Industries and other petrochemical businesses; Anil took over the financial arm, as well as the energy and information technologies businesses. Anil also branched out into public life, becoming a member of parliament.

Two years later, the brothers continue to prosper. Together, their businesses account for 12 per cent of the $1.3 trillion of wealth at the Indian bourses and have outpaced the astonishing growth in Indian stocks this year.

By some calculations, given the rise in the Indian stock market and the appreciation of the Indian rupee, Mukesh is worth anything between $44 billion and $60 billion, making him wealthier than Bill Gates. On his wife’s recent birthday, Mukesh bought her an executive jet, which they park in a private hangar.

At $38.5 billion, younger brother Anil’s net worth is not far behind. And he, too, owns a private jet—but his stays on the open tarmac.

Meanwhile, Mukesh’s business has expanded abroad: He now has investments in the Kurdish autonomous region of northern Iraq and Malaysia. In India, he has entered the retail sector, hoping to establish supermarkets that will compete with Wal-Mart before its entry into the Indian market. And a refinery his father wanted built in Jamnagar is up and running, with a capacity of 27 million tons a year.

Anil is not to be outdone. His telecommunications business, which uses the code division multiple access (CDMA) technology—a rival of the more prevalent global system of mobile, or GSM, communications—recently received clearance to expand into GSM services as well, to the protests of existing GSM providers Vodafone and Mittal. He has also bid to build the Delhi Metro’s extension connecting the city’s train station to the airport, a surefire money spinner. Meanwhile, his flagship company, Reliance Power, which accounts for nearly two-thirds of his business, is set to launch an initial public offering soon and may raise as much as $3 billion.

But Reliance Power’s IPO has once again pit the Ambani brothers against each other: Anil needs gas from the Krishna-Godavari gas project, a $4 billion venture under Mukesh’s belt. When the brothers parted ways, it was assumed that gas from Mukesh’s fields would feed Anil’s pipelines. Now a nasty price dispute has put the entire project on hold. The brothers are trying to sort out their differences under a court-appointed deadline.

The brothers’ mutual acrimony could reinforce the perception that family wealth is invariably destroyed by subsequent generations. Or the two could rise to the occasion and become a textbook example of a velvet divorce. The Ambani brothers are smart enough to realize that business is business, after all, and integrating businesses was the foundation on which Dhirubhai built his empire. Will they be their father’s sons?

Mr. Tripathi, a former Singapore correspondent of the REVIEW, is a writer based in London.