Sell in May and Go Away

Barry Armstrong
Founder and President, Armstrong Advisory Group

If you are an investor, you have probably heard the old adage, “Sell in May and go away.” It implies that the market tends to underperform during the period between May and October. Although some investors use the concept to inform their investment strategies, there is a continuing debate about whether it is a reliable rule of thumb. I thought it would be interesting to dig deeper and determine which side of that debate is right.

The Historical Data

According to 2012 report written by three University of Miami professors, returns from 37 markets over a period of 14 years showed that stock market returns were 10% higher during the period between November and April than the period between May and October (1). In the report, the authors determined that the “out-of-sample persistence” of their findings is more indicative of a broader trend than a series of statistical outliers (1). Reports like this lend a great deal of credence to those who believe that the adage is an accurate indicator of market trends.

The Caveats

Although the historical data is indicative of lower market performance from May to October, each year is different. For example, markets tend to outperform during the third year of an American president’s four-year term (2). There is also evidence indicating that the market’s performance is stronger during the year immediately following a presidential election (3). While the long-term trends show that the adage is surprisingly indicative, it is important to remember that no two years are the same and the market’s performance in the past provides no guarantees regarding its performance now or in the future.


While it may sound easy to use an adage with supportive historical data when formulating an investment strategy, I would argue that it is more productive for investors to consider other more important factors to inform their plans. This is especially true if you are an investor who wants to focus on building a long-term plan instead of one that is subject to the whims of potentially unreliable seasonal changes. Some of these factors include tax circumstances, risk tolerance, and investment objectives. If you are an investor who is in need of guidance or a second opinion of your portfolio allocation, it may be useful to sit down with an independent investment advisor who is able to thoroughly analyze every aspect of your financial situation and help you formulate a comprehensive strategy with all of these key factors in mind.

Barry Armstrong has over 30 years of experience in the financial industry. He founded the Armstrong Advisory Group in 2004 and has been sharing his financial knowledge with New Englanders on a daily basis during his Boston-based radio broadcast for nearly 20 years. Learn more about Barry and the Armstrong Advisory Group at Securities offered through Securities America, Inc. Member FINRA/SIPC and Advisory Services offered through Securities America Advisors. Barry Armstrong, Representative. Representatives of Securities America do not offer tax advice. Always seek the assistance of a tax professional familiar with the laws in your state. Armstrong Advisory Group and Securities America are unaffiliated. May 2018

1 Andrade, Sandro C. and Chhaochharia, Vidhi and Fuerst, Michael E., ‘Sell in May and Go Away’ Just Won’t Go Away (July 1, 2012). Financial Analysts Journal, Forthcoming. Available at SSRN: or
2 Chan, Kam Fong and Marsh, Terry, Buy Equities in Winter and Sell in May in Pre-Election Years: Market Premiums and Political Uncertainty in the Presidential Cycle (April 26, 2017). Available at SSRN: or
3 Hirsch, Jeffrey A. & Mistal, Christopher, May Almanac: Better in Post-Election Years (April 25, 2017). Available via Stock Trader’s Almanac: