Petrol station tycoons Mohsin and Zuber Issa struck a deal to acquire the supermarket giant from Walmart earlier this year after securing investment from TDR Capital.

Under the terms of the deal, the Issas and TDR would own equal stakes in Asda, with Walmart maintaining a minority shareholding.  

But the CMA has kicked off a phase one investigation into the proposed deal after it was referred to the regulator by the European Commission.