The Flash Crash of May 6, 2010, shook the confidence of market participants and raised questions about the market structure of electronic markets. In these markets, intraday intermediation has been increasingly provided by market participants without formal obligations to do so. We examine...

We study intraday market intermediation in an electronic market before and during a period of large and temporary selling pressure. On May 6, 2010, U.S. financial markets experienced a systemic intraday event - the Flash Crash - where a large automated selling program was rapidly executed in the...

We document a transaction level invariance relation among concurrent activity variables in the S&P 500 futures market: return volatility per transaction is proportional to the inverse of the squared expected trade size. It captures the time series behavior extremely well. Even more strikingly,...

We study a simple model of market making in which high-frequency market makers can cancel limit orders quickly after receiving an adverse signal. The resulting winner's curse induces low-frequency market makers to widen bid-ask spreads. Liquidity in the market may deteriorate unless...