UK supermarket Sainsbury's and its takeover target Asda have committed to deliver £1 billion of lower prices annually by the third year after completion of their proposed £7.3 billion deal.
The supermarket groups also said they would divest supermarkets and petrol forecourts across both brands but did not provide figures.
Sainsbury's and Asda are attempting to overturn brutal provisional findings from Britain's competition regulator, the Competition and Markets Authority (CMA), which is examining the deal.
The CMA said last month its initial view was that Sainsbury's purchase of Walmart's Asda should be blocked in the absence of the sale of a large number of stores, or even one of the brands.
Sainsbury's and Asda said they strongly disagreed with the CMA's findings and said the regulator's analysis contained "significant errors".
The two groups said they would invest £300m in the first year after combining and a further £700 over the following two years as cost savings flow through.
Sainsbury's and Asda had previously said they would lower prices on "everyday items" by around 10%, financed by cost savings from big multi-national suppliers but had not quantified the impact in cash terms.
The two groups said the price commitments would be independently reviewed, with the results published in order to hold them to public account.
Sainsbury's said it would cap its fuel gross profit margin to no more than 3.5 pence per litre for five years, while Asda will guarantee its existing fuel pricing strategy.
Sainsbury's also committed to pay small suppliers, with turnover with the business of less than £250,000, within 14 days, while Asda will continue to pay its small suppliers within 14 days.