The takeaway
Costco Wholesale Corp shows a moderate seasonal pattern over 10 years of data — strongest in November (+5.9%) and softest in October (+0.8%).
Right now
In July, the stock has risen 70% of years, averaging +4.1%, about +1.9 pts better than the S&P 500.
The full picture
Costco Wholesale Corp's most dependable month has been November, higher in 9 of 10 years; October has been its least reliable, up just 30% of the time.
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Month by month
The stock's clearest edge over the S&P 500 lands in November (+3.6 pts); it has trailed the market most in December (−2.1 pts).
“vs S&P” is Costco Wholesale Corp’s average for a month minus the S&P 500’s average for that same month — isolating Costco Wholesale Corp’s own seasonal edge from broad market drift.
Reality check
Over the last 5 years, November has closed higher 80% of the time versus 90% across the last 10 years — the pattern is holding.
Figures are the typical (median) November return and how often it rose — the last 5 years versus the last 10(the heatmap’s default window). This verdict stays anchored to that 10-year window even if you zoom the chart, so it never disagrees with the badges above.
In plain English
Dependability is the through-line here. November stands out, higher in 9 of 10 Novembers, but it heads a clutch of months that pull the year reliably upward.
Its average (+5.9%) and median (+7.1%) land within a hair of each other — the tell of steady, year-after-year gains rather than one outlier doing the work. It is among its calmest months, too, its returns swinging least from year to year (a 4.7% spread), and even its worst November in 10 years lost only 1.6% — the gentlest downside anywhere on its calendar. Crucially, the gain is the stock's own rather than a rising tide's: November has cleared the S&P 500 by +3.6 points above the index. That consistency sets it apart from the field, where the average stock manages November only about 62% of the time.
A few other months pull their weight: January, April, and May have also closed higher more often than not. At the other end of the calendar, October is the year's low point, though even there the stock has stayed positive on average (+0.8%), a sign every month leans up, and the edge isn't year-round — the stock has trailed the S&P 500 in December and September. Its roughest month on record was a −12.2% December in 2018 — a reminder of how hard even a seasonal name can fall.
A long streak recently broke — November had risen 9 years straight before a −1.6% reading in 2025. Reassuringly, the tendency has held its shape: the recent five years still track the years behind them.
The takeaway is less about when to buy than what to expect: November aside, the stock's months offer little reliable tilt.
Short answers on the stock's best month (November), its worst (October), and whether it really trades seasonally.
Yes, to a moderate degree. Since 2016 its best month (November, +5.9%) has run well ahead of its worst (October, +0.8%) — the heatmap above shows how steady that gap has been year to year.
November has been the strongest, averaging +5.9% and closing higher in 9 of 10 years since 2016.
It's the weakest month, but it has still averaged a small gain (+0.8%) — quiet rather than genuinely bad.
Explore
These names have the strongest July track records on record — a starting point for comparison.
Before you trade