Going Back to the Basics – Rethinking Market Efficiency RICHARD B. OLSEN,MICHEL M. DACOROGNA, ULRICH A. M ¨ ULLER, AND OLIVIER V. PICTET RBO.1992-09-07 December 2, 1992 A discussion paper by the O&A Research Group The purpose of this paper is to promote discussions and the exchange of ideas. Comments on the concepts presented are gratefully received.