High-speed computerized trading, often called "high-frequency trading" (HFT), has increased dramatically in financial markets over the last decade. In the US and Europe, it now accounts for nearly one-half of all trades. Although evidence suggests that HFT contributes to the efficiency of...

Traditional market makers are losing their importance as automated systems have largely assumed the role of liquidity provision in markets. We update the model of Glosten and Milgrom (1985) to analyze this new world: we add multiple securities and introduce an automated market maker who prices...

Garbade and Silber (1979) demonstrate that an asset will be liquid if it has (1) low price volatility and (2) a large number of public investors who trade it. Although these results match nicely with common notions of liquidity, one key element is missing: liquidity also depends on (3) an asset...