Does Costco (COST) stock go up or down depending on the month?
Costco month by month, year by year
| Year | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2026 | +9.0% | +7.5% | -1.4% | +1.8% | -5.7% | -2.2% | +1.8% | |||||
| 2025 | +6.9% | +7.0% | -9.8% | +5.2% | +4.6% | -4.8% | -5.1% | +0.4% | -1.9% | -1.5% | +0.2% | -5.6% |
| 2024 | +5.3% | +7.1% | -1.5% | -1.3% | +12.0% | +5.0% | -3.3% | +8.6% | -0.7% | -1.4% | +11.2% | -5.7% |
| 2023 | +12.0% | -5.3% | +2.6% | +1.3% | +1.7% | +5.2% | +4.1% | -2.0% | +2.9% | -2.2% | +7.3% | +11.4% |
| 2022 | -11.0% | +2.8% | +10.9% | -7.7% | -12.3% | +2.8% | +12.9% | -3.5% | -9.5% | +6.2% | +7.5% | -15.3% |
| 2021 | -6.5% | -6.1% | +6.5% | +5.6% | +1.7% | +4.6% | +8.6% | +6.0% | -1.3% | +9.4% | +9.7% | +5.3% |
| 2020 | +3.9% | -8.0% | +1.4% | +6.3% | +1.8% | -1.7% | +7.4% | +6.8% | +2.1% | +0.7% | +9.5% | -3.8% |
| 2019 | +5.4% | +1.9% | +10.7% | +1.4% | -2.4% | +10.3% | +4.3% | +6.9% | -2.3% | +3.1% | +0.9% | -2.0% |
| 2018 | +4.7% | -2.0% | -1.3% | +4.6% | +0.5% | +5.4% | +4.7% | +6.6% | +0.8% | -2.7% | +1.2% | -11.9% |
| 2017 | +2.4% | +8.1% | -5.4% | +5.9% | +1.6% | -11.4% | -0.9% | -1.1% | +4.8% | -2.0% | +14.5% | +0.9% |
| 2016 | -6.4% | -0.7% | +5.0% | -6.0% | +0.4% | +5.6% | +6.5% | -3.1% | -5.9% | -3.0% | +1.5% | +6.7% |
| 2015 | +0.9% | +2.8% | +3.1% | -5.6% | -0.3% | -5.3% | +7.6% | -3.6% | +3.2% | +9.4% | +2.1% | +0.0% |
| 2014 | -5.6% | +4.0% | -4.4% | +3.6% | +0.3% | -0.7% | +2.1% | +3.0% | +3.5% | +6.4% | +6.6% | -0.3% |
| 2013 | -1.0% | +4.8% | +2.2% | +1.1% | +0.9% | +6.2% | -4.7% | +2.9% | +2.5% | +6.3% | -5.1% | |
| Average | +1.6% | +1.3% | +1.5% | +1.2% | +0.4% | +1.0% | +4.1% | +1.6% | -0.1% | +1.9% | +6.0% | -2.0% |
| % of years up | 69% | 57% | 57% | 71% | 71% | 57% | 79% | 54% | 54% | 54% | 100% | 38% |
| Years observed | 13 | 14 | 14 | 14 | 14 | 14 | 14 | 13 | 13 | 13 | 13 | 13 |
Costco month by month: the summary
Over 2013-2026, here's what Costco (COST) stock did each month, on average: January +1.6% (up 69% of 13 years), February +1.3% (up 57% of 14 years), March +1.5% (up 57% of 14 years), April +1.2% (up 71% of 14 years), May +0.4% (up 71% of 14 years), June +1.0% (up 57% of 14 years), July +4.1% (up 79% of 14 years), August +1.6% (up 54% of 13 years), September -0.1% (up 54% of 13 years), October +1.9% (up 54% of 13 years), November +6.0% (up 100% of 13 years), December -2.0% (up 38% of 13 years). In other words, COST historically rose in January, February, March, April, May, June, July, August, October, November, and fell in September, December.
Does Costco really go up in November?
Over 2013-2026, November is Costco's strongest month: +6.0% on average, positive in 13 of 13 years. At the other end, December shows -2.0%. But a monthly gap is often built on one or two extreme years — the table above shows it: look at the spread, not just the average. Seasonality only means something when it has a cause (selling season, earnings calendar, year-end tax effects); with no identified cause, it's probably noise.
Frequently asked questions
Does Costco stock go up or down in August?
Over 13 years, COST rose +1.6% on average in August, finishing the month up 7 times out of 13 (54%). Median: +0.4%. Results are split year to year — there's no clear pattern. ⚠️ 13 years of data is not a prediction.
Does Costco stock go up or down in July?
Over 14 years, COST rose +4.1% on average in July, finishing the month up 11 times out of 14 (79%). Median: +4.5%. It's one of its most consistent months. ⚠️ 14 years of data is not a prediction.
Does Costco stock go up or down in October?
Over 13 years, COST rose +1.9% on average in October, finishing the month up 7 times out of 13 (54%). Median: +0.7%. Results are split year to year — there's no clear pattern. ⚠️ 13 years of data is not a prediction.
Does Costco stock go up or down in January?
Over 13 years, COST rose +1.6% on average in January, finishing the month up 9 times out of 13 (69%). Median: +3.9%. Results are split year to year — there's no clear pattern. ⚠️ 13 years of data is not a prediction.
Does Costco stock go up or down in March?
Over 14 years, COST rose +1.5% on average in March, finishing the month up 8 times out of 14 (57%). Median: +2.0%. Results are split year to year — there's no clear pattern. ⚠️ 14 years of data is not a prediction.
Does Costco stock go up or down in February?
Over 14 years, COST rose +1.3% on average in February, finishing the month up 8 times out of 14 (57%). Median: +2.3%. Results are split year to year — there's no clear pattern. ⚠️ 14 years of data is not a prediction.
What is the best month to buy Costco stock?
Historically, November: over the last 14 years, COST gained +6.0% on average that month and finished up 100% of the time (13 years observed). December is the weakest month (-2.0%). This is not a prediction: 14 years is a small sample, and the past is under no obligation to repeat.
Does the holiday season push Costco stock up?
Historically, over 14 years, November is Costco's best month (+6.0% on average, up 100% of years). November marks the start of the holiday shopping season for a retailer like Costco. ⚠️ This is a past tendency over a short history, not a rule — the holiday season is already anticipated by the market. Use it as context, never as a buy plan.
Why is Costco stock weaker in December?
December has averaged as its weakest month over 14 years (-2.0%, up only 38% of years). No clearly established recurring seasonal driver explains this month — it's a statistical tendency over 14 years of history, not a prediction.
Is there a best month to invest in the stock market in general?
There's no universal rule: every stock has its own seasonality. For COST it's November (+6.0% on average over 14 years) — another stock will look completely different. The calendar effects people cite ("sell in May", the year-end rally) are market-wide averages, not laws: on COST, November is the most consistent month (100% positive years). We also rank all 12 months for the whole market.
Does stock seasonality actually work?
Careful. A month that rose 14 times out of 14 can simply be chance: with 12 months and a dozen years, patterns appear naturally even in random data. Seasonality describes what happened; it doesn't explain why and predicts nothing. Treat it as context, never as a standalone buy signal.
What data is this table based on?
On COST's real monthly closing prices from 2013 to 2026 (14 years), source Yahoo Finance. Each cell = the price change over that month. Price performance, excluding dividends. Incomplete months and quote gaps are excluded.