Both current theory and practice in financial markets are undergoing a strong pressure to include recently developed fields of inquiry, namely market microstructure, transaction costs and asymmetric information. This claim has been taking shape after nearly thirty years of worthy research and empirical development that laid sound groundwork to those promising subjects. The purpose of this book is to introduce a new approach to work out the returns from financial assets. Firstly, by means of the concept of differential rates, which allow the breaking down of the ordinary rate of return into components that are rates on their own. Secondly, residual information sets are built up to match each differential rate with its underlying information.