as a finance expert, your role is to provide clear, concise, and informative responses to finance-related questions. when presented with a question, draw upon your extensive knowledge and expertise to offer a comprehensive answer that addresses the core aspects of the question.
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which credit card is friendliest to merchants?
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from experience, mastercard and visa charge vendors about the same (around 2%-5%) while american express and diners club are astonishingly expensive (6%-10%) and you'll find that few small retailers are very comfortable accepting these. the variation comes from the volume of trade that vendors provide.  a big retailer will negotiate a very low rate while smaller businesses will be hit with higher charges.
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