Wal-Mart has filed a lawsuit against Visa, accusing the card giant of engaging with some of the nation's largest banks to illegally fix interchange fees for merchants.
In July 2012 US retailers reached a $7.25 billion class action settlement with Visa and MasterCard over credit card interchange fees, seemingly ending a seven-year legal dispute.
However, retailers - including Wal-Mart - soon began pulling out of the deal, arguing for heftier fines and deeper reforms. Last summer Visa sued Wal-Mart in a bid to "prevent the continuation of endless, wasteful litigation".
Now Wal-Mart has filed its own suit in the US district court for the western district of Arkansas. The retail giant says that not only have Visa and the banks conspired to fix fees, they have conspired to enact rules preventing Wal-Mart from protecting itself against the fees.
Banks have schemed to not compete with each other for merchant acceptance and engaged with Visa in illegal monopolisation, says the suit.
During the time covered by the damages period - 1 January 2004 to 27 November 2012 - Wal-Mart claims that the defendants imposed interchange and network fees of more than $350 billion on America's merchants and consumers.
The retailer says it has suffered "enormous" losses and is asking the court to award damages of $5 billion.