This paper examines the use, determinants, and impact of anonymous orders in a market where disclosure of broker identity in the trading screen is voluntary. We find that most trading occurs nonanonymously, contrary to prior literature that suggests liquidity gravitates to anonymous markets. By strategically using anonymity when it is beneficial, traders reduce their execution costs. Traders select anonymity based on various factors including order source, order size and aggressiveness, time of day, liquidity, and expected execution costs. Finally, we report how anonymous orders affect market quality and discuss implications for market design.

We provide evidence on market structure and the cost of raising capital by examining changes in market structure in U.S. equity markets. Only the Order Handling Rules (OHR) of the Nasdaq, the one reform that reduced institutional trading costs, lowered the cost of raising capital. Using a difference-in-differences framework relative to the New York Stock Exchange (NYSE) that exploits the OHR’s staggered implementation, we find that the OHR reduced the underpricing of seasoned equity offerings by 1–2 percentage points compared with a pre-OHR average of 3.6%. The effect is the largest in stocks with the largest reduction in institutional trading costs after the OHR.