“Sell in May and Go Away” Refuses to Die
Investment Myths are Hard to Kill Despite the Evidence
Some investment myths persist despite overwhelming evidence against them. “Sell in May and go away” is a perfect example—a strategy that sounds clever but crumbles under scrutiny.
The Grain of Truth Behind the Myth
There’s a reason this adage endures: historical data does show seasonal patterns. Since 1926, stocks have delivered stronger returns from November through April than from May through October. The numbers are striking: the S&P 500’s annualized premium over one-month Treasury bills was 10.65% during the winter months compared to just 3.78% during the summer months—a difference of nearly 3-to-1.
The May-to-October period also experienced negative returns more frequently, with 33% of six-month periods in the red versus 27% for November-to-April periods.
So why not follow this pattern?
The Critical Detail Everyone Ignores
Here’s what the “sell in May” crowd conveniently overlooks: the May-through-October portfolio still delivered a positive annualized equity risk premium of 3.32% over Treasury bills. In other words, staying invested still outperformed cash on average.
Consider 2025 as a recent case study. Vanguard’s S&P 500 ETF (VOO) returned 27.3% from May through October, crushing the 2.1% return from one-month Treasury bills by 25.2 percentage points. In fact, with the sole exception of the bear market year of 2022, you’d have to go all the way back to 2011 to find the last time “sell in May” actually beat a consistently invested portfolio.
Why This Strategy Defies Logic
The “sell in May” strategy violates a fundamental principle of investing: the positive relationship between risk and expected return. To believe stocks should underperform Treasury bills from May to October, you’d also have to believe stocks become less risky during those months—an argument that makes no economic sense. Stocks don’t suddenly shed their volatility when the calendar flips to May. Market risk doesn’t take a summer vacation.
The Bottom Line
Despite its poor track record, this myth survives because it’s memorable and gets recycled by the financial media every spring. But memorable doesn’t mean profitable. The evidence is clear: staying invested beats trying to time the market based on calendar patterns.
You can be certain we’ll hear about “sell in May” again next spring. When you do, remember the numbers—and stay invested.
Larry Swedroe is the author or co-author of 18 books on investing, including his latest, Enrich Your Future: The Keys to Successful Investing