The Best Month to Buy Stocks: 30 Years of S&P 500 Data

Short answer: over the past three decades, the strongest month to have bought the S&P 500 was October, followed by March and November. The weakest was February, with September and midsummer close behind. That surprises most people, because the two things everyone thinks they know about stock market seasonality turn out to be half wrong.

We pulled this from 30 years of daily S&P 500 history. For every trading day since the mid-1990s we measured the return over the next 20 trading days, roughly a month, using the next open to the closing price so it reflects what you could actually capture. Then we grouped those returns by calendar month. Here is what fell out.

The best and worst months to buy stocks, ranked

Month	Avg forward return (~1mo)	Win rate	Median
October	+2.25%	76.5%	+2.25%
March	+1.76%	67.5%	+1.92%
November	+1.50%	74.1%	+1.84%
April	+1.46%	66.2%	+1.38%
June	+1.03%	68.6%	+1.48%
December	+0.89%	66.7%	+1.42%
May	+0.87%	64.1%	+1.50%
January	+0.75%	64.2%	+1.43%
July	+0.24%	56.4%	+0.56%
August	+0.13%	61.8%	+1.15%
September	−0.02%	58.0%	+0.87%
February	−0.14%	56.5%	+0.96%

Two numbers matter per month, not one. The average return tells you the typical size of the move. The win rate tells you how often it was positive at all. October wins on both, positive 76.5% of the time at more than two percent on average. February is the only month with a negative average, and it is barely better than a coin flip on direction.

Isn’t October the crash month?

No. Over 30 years it has been the single best month to buy, higher three times out of four.

That reputation for danger is the first myth. October owns the two most famous single-day crashes in history, 1929 and 1987, so it feels dangerous. The full record says the opposite. A couple of terrifying headlines stuck in the collective memory. The other 30 Octobers, quietly positive, did not.

This is what a base rate is for. It replaces the vivid story you remember with the frequency of what actually happened. The crash is real. It is also rare, and the reputation it earned does not match the average outcome.

Isn’t September the worst month?

Close, but no. September is soft, yet February was the actual low point in the data.

This myth is nearer the truth than the last one. September does carry the weak-spot reputation, and its 58% win rate is genuinely poor. But its average return over the next month came out roughly flat, not deeply negative. February posted the only negative average in the set and the second-worst win rate.

So the folk wisdom points at the right season, early-to-mid year weakness, but the wrong month. If you were going to name one month to be cautious buying, the data says February, not September.

What about “sell in May and go away”?

The old saying claims the market sleeps from May through October and does its real work from November through April. The record half agrees. Group the two halves and the winter window does average higher. But the single best month, October, sits at the tail end of the supposed dead season, which breaks the clean version of the rule.

I would not run a strategy off it either way. The gap between the strong half and the weak half is real but small, a fraction of a percent per month, and any single year can ignore the pattern entirely. Seasonality is a tilt, not a switch.

Has the pattern held, or is it drifting?

This is the question the generic seasonality posts never ask, and it is the one that matters most. A 30-year average can hide a pattern that quietly reversed. So we ran the same query on just the last ten years. Two things jumped out.

Sell in May has broken. Over the full record, summer was middling. In the last decade May and June were among the strongest months of all, up 2.1 and 2.5 percent on average with win rates above 82 percent. Whatever seasonal drag summer once carried is gone in the recent data.

February got worse, not better. Its recent average is negative 1.6 percent, positive less than half the time. The market’s real soft spot has sharpened rather than faded.

October held. Strong across the full record, strong across the last decade, right around a 79 percent win rate either way. Its reputation for danger stays wrong in every window we checked.

The lesson is not a fresh set of rules. It is that seasonality drifts, so a base rate is worth rechecking on recent data before you lean on it. The tidy averages that circulate in most articles are often decades stale.

How much should this actually change what you do?

Honestly, not much on its own. A month-of-year edge of one or two percent is a gentle tailwind, not a trading system. Buy good companies in February and plenty of them go up. Buy junk in October and plenty go down. The month is one weak factor among many stronger ones.

Where it earns its keep is as a tiebreaker and a expectation-setter. If you were already going to add to a position and the calendar says February, you might wait for a better setup. If it is October and the win rate is 76%, you can size with a little more confidence. It sharpens a decision you were already making. It does not make the decision for you.

Does this hold for individual stocks?

Sometimes, and often more sharply. The S&P 500 is an average of 500 names, so its seasonality is smoothed out. A single stock can carry a much stronger monthly pattern, usually tied to its own earnings calendar or a recurring demand cycle in its business. A retailer heading into the holidays and a chipmaker before a product season do not share the market’s seasonal shape.

That is the version worth checking before you lean on any of this: not “what does the market do in March,” but “what does this specific stock do, and how often.” The market-wide table above is the starting point, not the answer for any one name.

How we got these numbers, and how to check your own

Every figure here came from one query against 30 years of daily S&P 500 data: group each day by its calendar month, measure the return over the following 20 trading days, and report the average, the median, and how often it was positive. No model, no forecast, just the historical record counted honestly. That is all a base rate is, the frequency of what actually happened when conditions looked like they do now.

You can run the same thing for any ticker. TradeOdds indexes 35 years of history across roughly 3,200 stocks, ETFs, and crypto, with month-of-year built in as one of its match conditions. Ask it what a specific name has done in a specific month and it returns the base rate plus every matching day, so you are reading the source rows, not trusting a summary. Ask Stanley, the built-in analyst, will run it in plain English, or you can pull it straight through the API if you would rather script it.

FAQ

What is the best month to buy stocks historically?

For the S&P 500 over the past 30 years, October, with an average forward return near +2.25% and a positive rate of 76.5%. March and November are close behind.

What is the worst month for the stock market?

February, the only month with a negative average forward return in 30 years of S&P 500 data, narrowly worse than September.

Is “sell in May and go away” real?

Partly. The November-to-April window does average higher than May-to-October, but the single best month, October, falls inside the weak season, so the rule is a rough tilt rather than a hard pattern.

Should I time my investing around the calendar?

No. A month-of-year edge of one to two percent is small and unreliable in any single year. Use it as a minor tiebreaker, not a strategy.