The takeaway
MongoDB shows a pronounced seasonal pattern over 9 years of data — strongest in August (+13.8%) and softest in September (−4.2%).
Right now
In July, the stock has risen 75% of years, averaging +4.5%, about +2.3 pts better than the S&P 500.
The full picture
MongoDB's most dependable month has been August, higher in 7 of 8 years; September has been its least reliable, up just 25% of the time.
| Year | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Win rate % | ||||||||||||
| Median return % | ||||||||||||
| 2025 | ||||||||||||
| 2024 | ||||||||||||
| 2023 | ||||||||||||
| 2022 | ||||||||||||
| 2021 | ||||||||||||
| 2020 | ||||||||||||
| 2019 | ||||||||||||
| 2018 | ||||||||||||
| 2017 | — | — | — | — | — | — | — | — | — |
Month by month
The stock's clearest edge over the S&P 500 lands in August (+13.5 pts); it has trailed the market most in September (−4.0 pts).
“vs S&P” is MongoDB’s average for a month minus the S&P 500’s average for that same month — isolating MongoDB’s own seasonal edge from broad market drift.
Reality check
Over the last 5 years, August has closed higher 80% of the time versus 88% across the last 9 years — the pattern is holding.
Figures are the typical (median) August return and how often it rose — the last 5 years versus the last 9(the heatmap’s default window). This verdict stays anchored to that 9-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. August stands out, higher in 7 of 8 Augusts, but it heads a clutch of months that pull the year reliably upward.
The headline flatters a touch — its +13.8% average sits well above the +7.8% a typical year delivers, the work of a few big Augusts. That reliability comes with real swings, mind — even August ranges by 16.3% from year to year, so any single year can land far from the average. Crucially, the gain is the stock's own rather than a rising tide's: August has cleared the S&P 500 by +13.5 points above the index. That consistency sets it apart from the field, where the average stock manages August only about 52% of the time.
The strength clusters rather than stands alone — May–August forms a firm stretch that carries much of the year. The weaker half of the year is plainer: September has been the soft spot — the weakest of 2 months that average a loss (−4.2%), and the edge isn't year-round — the stock has trailed the S&P 500 in September and April. Its roughest month on record was a −36.8% May in 2024 — a reminder of how hard even a seasonal name can fall.
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: August aside, the stock's months offer little reliable tilt. With a short 9-year record and returns that swing hard year to year, the signal is best held loosely.
Short answers on the stock's best month (August), its worst (September), and whether it really trades seasonally.
Yes, to a pronounced degree. Since 2017 its best month (August, +13.8%) has run well ahead of its worst (September, −4.2%) — the heatmap above shows how steady that gap has been year to year.
August has been the strongest, averaging +13.8% and closing higher in 7 of 8 years since 2017.
It's the weakest, averaging −4.2% — historically a soft spot, though it still varies from year to year.
Explore
These names have the strongest July track records on record — a starting point for comparison.
Before you trade