“…Numerous measures of market quality are used in the microstructure literature, including such measures as spreads, depth, volatility, price impact, price efficiency, market efficiency, execution speed, order flow fragmentation, speed of price adjustment, locked/crossed markets, and market quality index (Theobald & Yallup, 2004;Bennett & Wi, 2006;Zhao & Chung, 2007;Eom, Ok, & Park, 2007;Hendershott & Jones, 2008;Alexander & Peterson, 2008;Shkilko, Van Ness, & Van Ness, 2008). Since the Rule 605 data contains market quality characteristics on spreads, rate of price improvement, amount of price improvement, and fragmentation of order flow, this study focuses on these measures of market quality.…”