The stock market’s favorite season starts Monday. For decades, November through April has beaten the rest of the year by a mile.
That’s the Halloween indicator, also called the “best six months” or “sell in May.” Buy stocks at the end of October, hold them through April, then step aside for the summer.
Yale Hirsch found the pattern in 1986. “You can divide the year into two sections and have practically all the gains in one six-month section and very little in the other,” his son Jeffrey Hirsch, editor in chief of the Stock Trader’s Almanac, wrote in the 2026 edition.
Since 1950, the Dow Jones Industrial Average (^DJI) has gained an average of about 7% from November through April, versus less than 1% from May through October, according to the Stock Trader’s Almanac. Put $10,000 into only the good half each year, and it grew to about $1.3 million. Put it into only the bad half, and it shrank to about $4,300.
This has held up since its discovery. In the 39 years after 1986, the good half turned $10,000 into about $1.2 million, versus about $5,800 for the bad half, by the Stock Trader Almanac’s count.
The ‘worst 6 months’ aren’t so bad anymore
By Yahoo Finance calculations, the S&P 500 (^GSPC) gained an average of about 7% from November through April between 1950 and 1987, versus about 1% from May through October.
Since 1988, the summer stretch has averaged about 3%. Over the past 10 years, the two halves have been dead even, at about 7% each. May through October came out ahead in five of those years, including a gain of about 23% in 2025.
Hirsch has seen the calendar shift too. “Anticipators, shifts in cultural behavior and faster information flow have altered seasonality in recent years,” he wrote.
Index funds and 401(k)s now keep money flowing into stocks every month — one reason “sell in May” has been a bad strategy this century. This year, the S&P 500 is up about 6% since the end of April.
Midterm years are where the good half still shines.
In midterm election years since 1950, October and November have been the S&P 500’s two best months, according to the Stock Trader’s Almanac. And the November-April stretch after a midterm has risen 19 straight times since 1950, with an average gain of about 15%, by Yahoo Finance calculations. That follows stocks’ best stretch of a midterm year, the eight sessions around Election Day.
None of this makes summer safe. May through October hold some of the market’s worst stretches, including drops of about 15% in 2001, about 18% in 2002, and about 30% in 2008. The better lesson may be to hedge in May rather than go away.
