Third market broker-dealers: Cost competitors or cream skimmers?

This article compares the bid-ask spread for New York Stock Exchange (NYSE)-listed securities before and after a major third market broker-dealer, Bernard L. Madoff Investment Securities (Madoff), begins to selectively purchase and execute orders in those securities. Tests reveal the quoted bid-ask spread tightens when Madoff enters the market. Furthermore, trading costs as measured by the difference between the transaction price and the midpoint of the contemporaneous bid-ask spread do not increase. Together, these results suggest that the adverse selection problem associated with allowing agents to selectively execute orders in exchange-listed securities may be economically insignificant.