TDR Capital is closing in on a deal to buy gas-station billionaire Zuber Issa’s stake in Asda as the private-equity firm tightens its grip on one of Britain’s biggest supermarket chains, according to people familiar with the discussions. The agreement for Issa’s 22.5% stake would give TDR majority control and could be announced in coming weeks, the people said, asking not to be named with negotiations in flux. They declined to specify the terms being discussed. TDR’s holding in Asda would rise to about two-thirds, while the transaction would further the dismantling of the relationship between brothers Zuber and Mohsin Issa. The brothers teamed up with London-based TDR to buy Asda for £6.8 billion ($8.45 billion) just three years ago from Walmart Inc. Their tenure has been rocky, with critics questioning the new owners’ commitment to Asda’s historic focus on keeping prices low. As food and gas prices surged in 2023 amid historic inflation, Asda, the third-largest UK grocer, had to rebut claims by Britain’s antitrust regulator that it was gouging customers. Born in Blackburn, England, the sibling duo founded EG Group and built up a $30 billion empire of petrol stations and convenience stores across Europe, the US and...