based on payments volume , total volume , number of transactions and number of cards in circulation , visa is the largest retail electronic payments network in the world . the following chart compares our network with those of our major general-purpose payment network competitors for calendar year 2009 : company payments volume volume transactions cards ( billions ) ( billions ) ( billions ) ( millions ) visa inc. ( 1 ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .