The takeaway
AstraZeneca PLC shows a moderate seasonal pattern over 10 years of data — strongest in May (+3.3%) and softest in January (−1.4%).
Right now
In July, the stock has risen 80% of years, averaging +3.2%, about +1.1 pts better than the S&P 500.
The full picture
AstraZeneca PLC's most dependable month has been May, higher in 9 of 10 years; January has been its least reliable, up just 20% of the time.
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Month by month
The stock's clearest edge over the S&P 500 lands in February (+2.8 pts); it has trailed the market most in October (−2.8 pts).
“vs S&P” is AstraZeneca PLC’s average for a month minus the S&P 500’s average for that same month — isolating AstraZeneca PLC’s own seasonal edge from broad market drift.
Reality check
Over the last 5 years, May has closed higher 80% of the time versus 90% across the last 10 years — the pattern is holding.
Figures are the typical (median) May 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. May stands out, higher in 9 of 10 Mays, but it heads a clutch of months that pull the year reliably upward.
A typical May brings +2.3%, a shade under the +3.3% average. It is among its calmest months, too, its returns swinging least from year to year (a 4.0% spread), and even its worst May in 10 years lost only 0.6% — the gentlest downside anywhere on its calendar. Crucially, the gain is the stock's own rather than a rising tide's: May has cleared the S&P 500 by +2.6 points above the index. That consistency sets it apart from the field, where the average stock manages May only about 55% of the time.
The strength clusters rather than stands alone — March–May forms a firm stretch that carries much of the year. The weaker half of the year is plainer: January has been the soft spot — the weakest of 3 months that average a loss (−1.4%), and the edge isn't year-round — the stock has trailed the S&P 500 in October, November, and January. Its roughest month on record was a −14.2% October in 2016 — a reminder of how hard even a seasonal name can fall.
At its steadiest, May strung together 7 straight positive years. 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: May aside, the stock's months offer little reliable tilt.
Short answers on the stock's best month (May), its worst (January), and whether it really trades seasonally.
Yes, to a moderate degree. Since 2016 its best month (May, +3.3%) has run well ahead of its worst (January, −1.4%) — the heatmap above shows how steady that gap has been year to year.
May has been the strongest, averaging +3.3% and closing higher in 9 of 10 years since 2016.
It's the weakest, averaging −1.4% — 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