Do fast, competitive markets yield liquidity measurement problems when using the popular Monthly Trade and Quote (MTAQ) database? Yes. MTAQ yields distorted measures of spreads, trade location, and price impact compared with the expensive Daily Trade and Quote (DTAQ) database. These problems are...

We investigate how the increase in speed of U.S. equity markets has distorted liquidity measures. We find that the widely-used Monthly Trade and Quote (MTAQ) database yields a percent effective spread 43% higher than our benchmark, a quoted spread that is nonpositive nine times more often, and a...