The takeaway
GlaxoSmithKline PLC ADR shows a moderate seasonal pattern over 10 years of data — strongest in March (+2.4%) and softest in February (−1.0%).
Right now
In July, the stock has fallen 50% of years, averaging −0.3%, roughly 2.4 pts behind the S&P 500.
The full picture
GlaxoSmithKline PLC ADR's most dependable month has been March, higher in 9 of 10 years; February has been its least reliable, up just 40% of the time.
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Month by month
The stock's clearest edge over the S&P 500 lands in January (+2.0 pts); it has trailed the market most in July (−2.4 pts).
“vs S&P” is GlaxoSmithKline PLC ADR’s average for a month minus the S&P 500’s average for that same month — isolating GlaxoSmithKline PLC ADR’s own seasonal edge from broad market drift.
Reality check
Over the last 5 years, March has closed higher 100% of the time versus 90% across the last 10 years — the pattern is holding.
Figures are the typical (median) March 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. March stands out, higher in 9 of 10 Marches, but it heads a clutch of months that pull the year reliably upward.
Its average (+2.4%) and median (+2.9%) land within a hair of each other — the tell of steady, year-after-year gains rather than one outlier doing the work. Crucially, the gain is the stock's own rather than a rising tide's: March has cleared the S&P 500 by +1.4 points above the index. That consistency sets it apart from the field, where the average stock manages March only about 56% of the time.
The strength clusters rather than stands alone — March–May forms a firm stretch that carries much of the year. On the other side of the ledger, February has been the soft spot — the weakest of 3 months that average a loss (−1.0%), and the edge isn't year-round — the stock has trailed the S&P 500 in July, October, and February. Its roughest month on record was a −21.1% August in 2022 — a reminder of how hard even a seasonal name can fall.
March has now closed higher 5 years running. 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: March aside, the stock's months offer little reliable tilt.
Short answers on the stock's best month (March), its worst (February), and whether it really trades seasonally.
Yes, to a moderate degree. Since 2016 its best month (March, +2.4%) has run well ahead of its worst (February, −1.0%) — the heatmap above shows how steady that gap has been year to year.
March has been the strongest, averaging +2.4% and closing higher in 9 of 10 years since 2016.
It's the weakest, averaging −1.0% — 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.
Before you trade