Visa U.S.A., Inc., MasterCard International, Inc., American Express (Amex), and Discover are the four major credit- and charge-card networks in the United States. Visa and MasterCard are joint ventures, owned by the thousands of banks that are their members. The banks issue the cards, clear transactions, and collect fees from the merchants that accept the cards. By contrast, Amex and Discover themselves issue cards to customers, process transactions, and collect fees. Since 1995, Amex has asked banks to issue its cards. No bank has been willing to do so, however, because it would have to stop issuing Visa and MasterCard cards under those networks' rules barring member banks from issuing cards on rival networks. The U.S. Department of Justice filed a suit in a federal district court against Visa and MasterCard, alleging in part that the rules were illegal restraints of trade under the Sherman Act. Do the rules harm competition? If so, how? United States v. Visa U.S.A., Inc., 344 F.3d 229 (2d Cir. 2003).