The takeaway
Cullinan Oncology LLC shows a pronounced seasonal pattern over 5 years of data — strongest in January (+9.2%) and softest in September (−14.0%).
Right now
In July, the stock has risen 60% of years, averaging +1.2%, roughly 0.9 pts behind the S&P 500.
The full picture
Cullinan Oncology LLC's most dependable month has been January, higher in 3 of 5 years; September has been its least reliable, up just 0% 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 |
Month by month
The stock's clearest edge over the S&P 500 lands in January (+9.4 pts); it has trailed the market most in September (−13.9 pts).
“vs S&P” is Cullinan Oncology LLC’s average for a month minus the S&P 500’s average for that same month — isolating Cullinan Oncology LLC’s own seasonal edge from broad market drift.
Reality check
Over the last 5 years, January has closed higher 60% of the time versus 60% across the last 5 years — the pattern is holding.
Figures are the typical (median) January return and how often it rose — the last 5 years versus the last 5(the heatmap’s default window). This verdict stays anchored to that 5-year window even if you zoom the chart, so it never disagrees with the badges above.
In plain English
There's a real but measured seasonal tilt here, toward January — the firmest corner of the calendar, higher in 3 of 5 Januaries.
The strength looks broad-based rather than freakish: its average (+9.2%) and median (+9.0%) sit close together, so no single blow-out year is flattering the figure. That reliability comes with real swings, mind — even January ranges by 23.6% from year to year, so any single year can land far from the average. Better still, that strength is the stock's own and not just a buoyant market — January has outpaced the S&P 500 by +9.4 points on average.
It doesn't stand entirely alone — February, July, and August have leaned firm as well, if less emphatically. The weaker half of the year is plainer: September has been the soft spot — the weakest of 6 months that average a loss (−14.0%), and the edge isn't year-round — the stock has trailed the S&P 500 in September, March, and June. Its roughest month on record was a −25.2% March in 2022 — a reminder of how hard even a seasonal name can fall.
Treat it as a tendency rather than a rule — seasonality describes the past, not a promise. With a short 5-year record and returns that swing hard year to year, the signal is best held loosely.
Short answers on the stock's best month (January), its worst (September), and whether it really trades seasonally.
Yes, to a pronounced degree. Since 2021 its best month (January, +9.2%) has run well ahead of its worst (September, −14.0%) — the heatmap above shows how steady that gap has been year to year.
January has been the strongest, averaging +9.2% and closing higher in 3 of 5 years since 2021.
It's the weakest, averaging −14.0% — 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.
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