The present work corroborates the existence of two anomalies that question the hypothesis of efficient markets in the Chilean stock market, these are the “effect weekend” or “effect monday” and the “effect month end”.
Using the daily values of closing of stock-exchange index IPSA, and following the methodology used by Kenneth R. French, the hypotheses “Trading Time” and “Calendar Time” were checked to contrast the “effect weekend”. In order to contrast the “effect month end” it was made an analysis of averages and variances and, later, a study of temporary windows