Summer portfolio (and Sell in May) – update 2026

I first wrote about the "Sell in May" phenomenon a decade ago in 2016  in my article "Should you sell in May and go away". The adage states that you "Sell in May and go away and don't come back till St. Leger Day", in other words, sell out of the stock market in May and stay in cash over the summer, before going back in at the start of September when the St Leger Stakes horse race is run. The theory is that by doing so you avoid the more volatile summer months, which historically have also tended to underperform the rest of the year. A study published in 2002 found evidence of the effect in the UK going back as far as 1694. In addition, the Sell in May effect was present in 36 out of 37 countries that the study looked at with it being strongest in European markets.