What are the best and worst months to buy stocks? For answers, investors have ransacked past stock returns, looking for patterns. Investopedia advises that, “The average return in October is positive historically, despite the record drops of 19.7% and 21.5% in 1929 and 1987.” The so-called January Effect argues for buying in December. The Santa Claus Rally argues for buying in November. As for selling, some say, “Sell in May and go away.” Others believe that August and September are the worst months for stocks. Such advice is wishful thinking by hopeful investors searching for an elusive way to time the market. The inconvenient truth is that there can be no permanent best or worst month. If December was the most profitable month for stocks, people would buy in November, temporarily making November the best month — causing people to buy in October, and so on. Any regular pattern is bound to self-destruct. Stock prices don’t go up or down because today is different from yesterday, but because today is not what the market expected it to be — the market is surprised. By definition, surprises cannot be predicted; neither can short-term price movements.via