As one of the oldest and most innovative financial institutions, a clearinghouse efficiently clears and settles payments for equity transactions as well as other securities. However, this paper will only be concerned with common and preferred equity securities. The purpose of a clearinghouse is to reduce counterparty risk. It acts as an intermediary between two parties, so that the risk of one party failing to honor its contractual obligation is diminished. It reduces settlement risk through netting, the process of eliminating offsetting transactions, thus decreasing the amount of cash flow. I examine the impact of the New York Stock Exchange Clearinghouse upon its establishment in May 1892. Specifically, I analyze the clearinghouse’s effect on trading costs for different equity securities, scrutinizing the effects on bid-ask spreads. I find that once a firm joined the NYSE clearinghouse, both its relative and absolute bid-ask spreads are narrowed, representing an overall reduction in spreads of 5.28 percent.