We measure the distribution of welfare losses from non-competitive behavior in the U.S. credit card industry during the 1970s and 1980s. The early credit card industry was characterized by regional monopolies. Ensuing legal decisions led to competitive reforms that resulted in greater, but still limited, oligopolistic competition. We measure the distributional consequences of these reforms by developing and estimating a heterogeneous agent, defaultable debt framework with oligopolistic lenders.