Discover Financial Services is seeking $6 billion in damages in a long running anti-trust lawsuit that accuses credit card rivals MasterCard and Visa of blocking its access to the bank-issued card market in the US.
The 2004 suit alleges anti-competitive business practices by MasterCard and Visa that effectively locked Discover out of the bank-issued card business in the US.
According to press reports the $6 billion claim was cited in legal papers that had been kept confidential but were unsealed in a court earlier this week.
MasterCard and Visa both dispute the claim for damages, which could potentially be tripled at a trial set for September in New York.
San Francisco-based Visa told reporters that the damages sought by Discover are "dramatically overstated", while MasterCard said Discover's claim is "baseless".
Discover and American Express both filed suit in 2004 after the US Supreme Court upheld a lower court ruling that found Visa and MasterCard violated antitrust laws by banning their member banks from issuing cards from rival firms.
Last November Visa agreed to pay American Express up to $2.25 billion to settle its case. However American Express is still seeking damages from MasterCard.