Long-short anomaly returns are strongly related to the day of the week. Anomalies for which the speculative leg is the short (long) leg experience the highest (lowest) returns on Monday. The opposite pattern is observed on Friday. The effects are large. Monday (Friday) alone accounts for over 100% of returns for all anomalies examined for which the short (long) leg is the speculative leg. Consistent with a mispricing explanation, the pattern is driven by the speculative leg. The observed patterns are consistent with the abundance of evidence in the psychology literature that mood increases on Friday and decreases on Monday.

We document evidence consistent with retail traders in the Forex market attributing random success to their own skill and, as a consequence, increasing risk taking. Although past performance does not predict future success for these traders, traders increase trade sizes, trade size variability, and number of trades with gains, and less with losses. There is a large discontinuity in all of these trading variables around zero past week returns: e.g., traders increase their trade size dramatically following winning weeks, relative to losing weeks. The effects are stronger for novice traders, consistent with more intense “learning” in early trading periods.