We test for the presence of long memory in daily stock returns and their squares using a robust semiparametric procedure. Spurious results can be produced by nonstationarity and aggregation.

In this paper we investigate the relation between expected return and firm size. Starting with the pionnering work of Banz (1981) and Reinganum (1981), this area has been one of the most researched topics in finance over the last 15 years.

The purpose of this paper is twofold. First, it introduces a new version of the Edgeworth process with trading activities centered around self-interested enterprising arbitragers; and second it examines how the prices of the derived securities are deteremined under this process.