The seasonal adage 'Sell in May and go away' has resurfaced in market conversations, but Deutsche Bank's most recent analysis concludes the strategy offers no reliable statistical advantage over a buy-and-hold approach.
In the fourth installment of its Myth Buster series on this trading rule, analyst Maximilian Uleer tested multiple permutations of the strategy across several equity indices, including the S&P 500, STOXX Europe 600, DAX and EURO STOXX 50. The study evaluated different entry and exit points to determine whether a seasonal timing rule produces consistent outperformance.
Among the variations examined, the approach that involves selling at the end of May and reinvesting at the end of September consistently produced the strongest simulated returns. Applied to the STOXX Europe 600 from 1987 onward, that particular timing rule generated 9.0% annualized returns compared with 7.4% for a continuous buy-and-hold approach.
However, Deutsche Bank cautioned that those headline figures mask important caveats. In absolute terms the seasonal strategy underperformed buy-and-hold in 25 of 39 years in the STOXX Europe 600 simulation. The bank also found that much of the apparent edge depends on a small number of steep summer downturns - specifically the sell-offs in 1998, 2001 and 2002. Excluding those episodes largely erases the strategy's advantage.
Performance over more recent periods was also mixed. Over the past decade, simulations showed the seasonal rule underperformed in eight of 10 years. U.S. equities produced similarly weak results under the tested permutations; the strategy outperformed the market in only 22 of 53 years in those simulations. For the EURO STOXX 50 and the DAX, Deutsche Bank reported hit ratios below 50% across all combinations tested.
Summing up the findings, Uleer wrote: "Our stance on 'Sell in May' remains unchanged: The strategy, in our view, offers no statistical edge over 'Buy and Hold' and its success is as random as betting on heads in a coin toss." The bank said it prefers a fundamentals-based investment approach rather than relying on seasonal patterns.
Context note: The analysis covered multiple entry and exit timing choices across the named indices and focused on historical simulations. Where the record is limited or heavily influenced by a few dramatic market events, Deutsche Bank highlighted that the seasonal strategy's apparent success is not robust.