The financial press is currently obsessed with a rhyme. "Sell in May and go away." It is the ultimate intellectual sedative. It suggests that by simply clicking a button and heading to the Hamptons, you can dodge the seasonal "dead zone" of the markets.
The typical analysis focuses on historical averages. They point to the S&P 500’s performance from May to October compared to the November to April "golden window." They tell you the returns are statistically lower. They show you charts of the 1950s.
They are wrong. Not because the math is false, but because the logic is lazy.
Following this adage is the quickest way to guarantee mediocrity. It ignores the cost of being out of the market, the tax implications of short-term gains, and the fundamental shift in how modern liquidity operates. If you are selling in May, you aren't a "shrewd operator." You are a victim of a psychological trap masquerading as a strategy.
The Liquidity Myth and the Ghost of the Trading Floor
The "Sell in May" mantra was born in a world that no longer exists. It comes from the old London Stock Exchange, where "St. Leger Day" marked the return of traders from their summer holidays. Back then, markets actually lacked liquidity in the summer. Big players left. Volume evaporated. Price swings became erratic.
Today? Markets are dominated by algorithms, high-frequency trading firms, and global sovereign wealth funds that do not take summer vacations.
The idea that the market "goes to sleep" is a fantasy. In fact, some of the most violent and profitable upward re-ratings happen when the "lazy money" is on the sidelines. By exiting the market, you aren't avoiding risk; you are assuming the massive risk of missing the fat tail events. If you miss just the ten best days of the year, your long-term returns don't just dip—they collapse. Many of those days happen in the heart of the "dead" summer months.
The Tax Man is Cheering for Your Exit
Let’s talk about the math the "Sell in May" crowd ignores: friction.
I have watched fund managers burn through millions in potential alpha because they couldn't resist the urge to "cycle out" of positions. When you sell in May, you trigger capital gains taxes. Unless you are trading in a tax-advantaged account, you are handing over a significant portion of your capital to the government just to follow a rhyme.
To break even on a "Sell in May" strategy, the market doesn't just have to go down or stay flat. It has to drop by enough to cover your:
- Short-term capital gains tax.
- Slippage on the exit.
- Slippage on the re-entry in November.
- Missed dividends.
In a world where the S&P 500 has an upward bias, you are betting against the house while paying a premium to sit at the table. It is mathematically illiterate.
The Correlation Fallacy
The "lazy consensus" argues that because the average return in summer is lower, you should avoid it. This is a misunderstanding of probability.
Imagine a scenario where a market returns 10% from November to April and 2% from May to October. The "Sell in May" advocate sees the 2% and calls it a waste of time.
But that 2% is still positive.
By sitting in cash, you are likely earning less than that after inflation and fees. More importantly, the volatility in that period often creates the entry points for the year-end rally. If you aren't in the game, you can't buy the July dip or the August correction. You end up chasing the market in November, buying back at higher prices than where you sold in May.
The Institutional Squeeze
Big money loves the "Sell in May" narrative. Why? Because it creates predictable retail behavior.
When retail investors pull back, volatility often increases on lower volume. This allows institutional desks to accumulate positions in high-conviction names at better prices. They are the ones buying your "seasonal exit."
I have sat in rooms where we tracked "retail sentiment shifts" based on these exact calendar myths. When the "Sell in May" headlines start peaking in late April, we look for the oversold signals. The "myth" becomes a self-fulfilling prophecy that savvy players exploit to squeeze the very people who think they are being clever.
Why 'Wait and See' is a Death Sentence
People often ask: "Is it a myth?"
The answer is: "It doesn't matter."
Even if the statistics favor a slight dip, the opportunity cost of being "out" is too high. We are currently in a technological super-cycle. Between energy transitions and the total overhaul of compute infrastructure, the macro drivers do not care about the date on a calendar.
If a major breakthrough in semiconductor efficiency or a massive shift in Fed policy happens in July, "Sell in May" followers are left staring at a screen, paralyzed. They won't buy back because "it's not November yet." They wait. The market moves 15% without them.
The Only Seasonality That Matters
If you want to be a contrarian who actually wins, stop looking at months and start looking at flow.
Watch the quarterly earnings cycles. Watch the Treasury's general account. Watch the repurchase agreements. These are the pipes through which money moves. They don't follow the Gregorian calendar.
The "Sell in May" crowd is looking at the shadow of the market, not the market itself. They are trying to find a shortcut to avoid the discomfort of a flat portfolio for three months. But wealth isn't built by avoiding boredom. It’s built by staying the course when the noise is at its loudest.
Stop Asking if the Myth is True
The question isn't whether "Sell in May" is a myth. The question is whether you are a tourist or an owner.
Tourists worry about the weather in July. Owners worry about the strength of the foundation. If you own high-quality assets, the calendar is irrelevant. Selling your winners because it's almost summer is like selling your house because you think it might rain next week.
It’s an amateur move dressed up as "tradition."
Growth doesn't take a summer break. Neither should your capital. If you’re looking for an excuse to exit, just admit you’re scared of a 5% drawdown. Don't blame the month of May for your lack of conviction.
The market doesn't owe you a profit just because you showed up in November. It rewards those who have the stomach to sit through the quiet, grueling months of July and August without flinching.
Put your phone away. Stay in the trade. Stop letting a nursery rhyme dictate your net worth.
