Responding to a September 2002 regulatory enforcement, the Island electronic communications network stopped displaying its limit order book in the three most active exchange-traded funds (ETFs) where it was the dominant venue. Island's share of trading activity and price discovery fell,...

In September 2008, the U.S. Securities and Exchange Commission (SEC) temporarily banned most short sales in nearly 1,000 financial stocks. We examine the ban's effect on market quality, shorting activity, the aggressiveness of short sellers, and stock prices. The ban's effects are concentrated...