Don’t Sell in May and Go Away

Analyzing the effectiveness of the “Sell in May and Go Away” strategy using historical S&P500 data and market dynamics.

5 min readMay 27, 2024

“Sell in May and Go Away” has long been a familiar phrase in the financial industry. This strategy recommends that investors should sell their stocks in May, stay out of the market during the summer months, and reinvest in November. Yet, a closer look at historical data and market trends suggests that this approach might not be as effective as it appears, especially within the US markets. In this article, we delve into why investors should be cautious about adhering to this saying and discuss alternative methods for navigating the market during the summer, focusing on the S&P500 index’s performance from 1929 to 2023. For a broader perspective on global markets, you might find the article “Sell in May and Go Away” Just Won’t Go Away insightful.

We also provide a Google Sheets spreadsheet containing aggregated data for your research purposes.

The analysis is based on historical data from the EODHD platform, which covers the S&P500’s historical data from 1929 to 2023. EODHD offers straightforward JSON APIs that include data on dividend payments, yields, ex-dates, and more, encompassing over 150,000 tickers from more than 70 global exchanges.

Additionally, our template libraries feature step-by-step guides for creating Excel and Google Sheets spreadsheets. These resources offer more information on our Ready-to-Go solutions.

Historical Background

The phrase “Sell in May and go away” originated in the United Kingdom, originally phrased as “Sell in May and go away, and come on back on St. Leger’s Day.” St. Leger’s Day, a horse race held in mid-September, marked the end of the summer holiday season. Historically, the summer months saw lower trading volumes and reduced market liquidity as traders and investors took holidays, sometimes leading to increased volatility and weaker stock performance during this period.

Variability in the Strategy’s Performance

Though some studies indicate that US stock markets historically underperform during summer, this pattern isn’t consistent year over year. This inconsistency challenges the reliability of the “Sell in May” strategy.

Opportunities Missed by Selling in May

By exiting the market in May and re-entering in November, investors could miss out on substantial gains. Historical data from 1929 to 2023 shows that sticking with a “Sell in May” approach would have led to an average annual return loss of 2.1% compared to a buy-and-hold strategy. Missing these gains can significantly affect long-term portfolio growth.

Performance Analysis

The chart of annual returns from the “Winter” period (November 1st to April 30th) and the “Summer” period (May 1st to October 31st) does not clearly indicate which period yields better results. The “Sell in May” strategy appears less clear-cut.

Histograms of Annual Returns

Histograms comparing annual returns for summer and winter from 1929 to 2023 show that summer periods contribute significantly to overall performance, albeit with a higher average and median return for winter periods.

Statistical Analysis Over Time

Combined statistical data indicates that the median returns for summer periods have increased over the years, making the difference between periods less pronounced. Factors contributing to this increase could include the growth of the non-cyclical IT sector and advancements in trading technologies.

Instead of missing out on potential gains by following the “Sell in May” strategy, investors could maintain a long-term focus, diversify their portfolios, and use dollar-cost averaging to mitigate short-term market fluctuations.

Evolving Market Conditions

While the “Sell in May” strategy is based on historical patterns, market dynamics have changed. Globalization, technological advancements, and the rise of algorithmic trading have altered market behavior. Relying on outdated strategies may not be effective in today’s environment.

Sector-Specific Impacts

The “Sell in May” strategy’s impact varies by sector. Sectors like consumer discretionary and tourism might see more seasonal effects, while sectors like healthcare and utilities might be less affected. Investors should consider these differences when evaluating the strategy..

Costs and Tax Implications of Frequent Trading

Frequent trading, as advocated by the “Sell in May” strategy, can lead to higher transaction costs and tax implications. These additional costs could negate the benefits of avoiding the summer months.

Final Thoughts

The “Sell in May and Go Away” strategy isn’t a clear-cut approach for US markets. Investors should weigh its limitations and consider alternative strategies such as maintaining a diversified portfolio, regular rebalancing, and basing decisions on fundamental analysis. Consulting with a financial advisor can provide personalized advice aligned with individual goals, risk tolerance, and investment horizons. By critically assessing the “Sell in May” strategy and exploring other methods, investors can better navigate the markets throughout the year.

Please note that this article is for informational purposes only and should not be taken as financial advice. We do not bear responsibility for any trading decisions made based on the content of this article. Readers are advised to conduct their own research or consult with a qualified financial professional before making any investment decisions.

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