We consider an extension of the Roll model where the trade direction, i.e. whether the trade is buyer or seller initiated, is multiplied by the dynamic quoted half-spread. Employing tick-by-tick maximum likelihood estimation on S&P 500 constituents, we find that the efficient price is quite...

This essay discusses some things we have learned about markets, in the process of designing marketplaces to fix market failures. To work well, marketplaces have to provide thickness, i.e. they need to attract a large enough proportion of the potential participants in the market; they have to...

This essay discusses some things we have learned about markets, in the process of designing marketplaces to fix market failures. To work well, marketplaces have to provide thickness, i.e. they need to attract a large enough proportion of the potential participants in the market; they have to...

The rational expectations efficient market model of the exchange rate has failed empirically. In this paper we develop a model of the exchange rate in which agents use simple forecasting rules. Based on an ex post evaluation of the relative profitability of these rules they decide whether to...

Small transaction costs and uncertainty imply that optimal cross-currency interest rate speculation is marked by a first-order hysteresis band. Consequently uncovered interest parity does not hold and market efficiency tests based on it are misspecified. Indeed measured prediction errors are a...