How often would you rely upon something that works only slightly more than half the time?
Probably not often, or maybe never. Nonetheless, looking for guidance to potential market performance, investors often rely on seasonal patterns with an occurrence frequency only modestly above 50%.
The “sell in May and go away” cliché seems to be supported by data for May through September, as no average monthly result in this period matches the overall monthly average. The S&P 500, on average, however, produced gains in May through September. The cliché might be better phrased as “sell in late August” since, on average, September cut the period gain by more than 70%.