The idea was that with so many sports-related social events in the summer months - Royal Ascot, Wimbledon, Henley Royal Regatta, Cowes Week, and ending with St. Leger flat race, on September 13 this year - that trading volumes plummet and stock market fortunes wane.  Notable summer periods when the market did fall sharply were 1992 (-11.6pc), 1998 (-12.6pc), 2001 (-18.4pc), 2002 (-21.2pc), 2008 (-13pc), and 2011 (-10.9pc).  If investors chose to sell in May and stay away, their average annualised market returns would have been better in only nine of the 25 years and as an average would be 9.8pc instead of 10.9pc. That does not include the dealing costs for buying and selling.  Jason Hollands, managing director of Bestinvest, said: "Gone are the days when the City brokers departed to spend a leisurely summer at sporting events. These days markets trade globally and around the clock. So if there was ever any truth in the ‘Sell in May’ theory, the evidence since the Big Bang City reforms suggests that while there have been a handful of significant summer sell-offs which mean ‘average’ returns for the summer months are low, there is no compelling case to automatically get out of the market each May; indeed such a strategy rigorously followed would have reduced average returns."  With the FTSE All-Share sitting on a loss of 1.3pc so far this year, will the market turn profitable later in the year?  As Mr Hollands rightly observes, "it is of course impossible to predict short-term movements in the markets with accuracy" but with uncertainty over the situation in Ukraine and fears about rate rises here and a slowdown in China, he expects "a period of choppier waters".
This chart of historic returns sheds some light on the wisdom of the City   adage that investors should sell in May and come back on St. Leger Day