2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/208873A quantitative check of weak efficiency in US dollar/German mark exchange rates is developed using high frequency data. We show the existence of long term return anomalies. We introduce a technique to measure the available information and show it can be profitable following a particular trading rule.22 pages, LaTeX, 6 eps figures, submitted to European Financial Management journalDisordered Systems and Neural NetworksStatistical Financetext