Calendar Effect

Calendar effect refers to a collection of theories which believe that a certain date or period of time is bad or good for investing in a certain security. These include the Monday Effect, January effect etc. In commodities, calendar effects may take place due to seasonal supply and demand shifts. In stocks, calendar effects may occur for psychological, fundamental or random reasons.

Most of the calendar effects are based on observation and anecdotal evidence, so it is hard to say whether or not they are necessarily predictive of the future. Ironically, some calendar effects have become rather muted as their knowledge became more widespread.