Sell in May and go away is an investment strategy for stocks based on a theory (sometimes known as the Halloween indicator) that the period from November to April inclusive has significantly stronger stock market growth on average than the other months.[1][2][3][4][5] In such strategies, stock holdings are sold or minimized at about the start of May and the proceeds held in cash (e.g. a money market fund); stocks are bought again in the autumn, typically around Halloween. "Sell in May" can be characterized as the belief that it is better to avoid holding stock during the summer period.
Though this seasonality is often mentioned informally, it has largely been ignored in academic circles.[citation needed] Analysis by Bouman and Jacobsen (2002) shows that the effect has indeed occurred in 36 out of 37 countries examined, and since the 17th century (1694) in the United Kingdom. The effect is strongest in Europe.[6]