The takeaway
Harmonic Inc shows a moderate seasonal pattern over 10 years of data — strongest in October (+5.8%) and softest in May (−1.3%).
Right now
In July, the stock has risen 70% of years, averaging +7.9%, about +5.8 pts better than the S&P 500.
The full picture
Harmonic Inc's most dependable month has been October, higher in 8 of 10 years; May has been its least reliable, up just 30% of the time.
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Month by month
The stock's clearest edge over the S&P 500 lands in July (+5.8 pts); it has trailed the market most in January (−5.4 pts).
“vs S&P” is Harmonic Inc’s average for a month minus the S&P 500’s average for that same month — isolating Harmonic Inc’s own seasonal edge from broad market drift.
Reality check
Over the last 5 years, October has closed higher 80% of the time versus 80% across the last 10 years — the pattern is weakening.
Figures are the typical (median) October 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
Strip the year back and a single month does the heavy lifting: October, up in 8 of 10 Octobers while the other eleven tend to blur together.
Its average (+5.8%) and median (+5.7%) land within a hair of each other — the tell of steady, year-after-year gains rather than one outlier doing the work. That reliability comes with real swings, mind — even October ranges by 13.7% 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: October has cleared the S&P 500 by +4.8 points above the index. That consistency sets it apart from the field, where the average stock manages October only about 53% of the time.
The strength clusters rather than stands alone — October–December forms a firm stretch that carries much of the year. The weaker half of the year is plainer: May has been the soft spot — the weakest of 4 months that average a loss (−1.3%), and the edge isn't year-round — the stock has trailed the S&P 500 in January, April, and February. Its roughest month on record was a −21.9% July in 2017 — a reminder of how hard even a seasonal name can fall.
At its steadiest, October strung together 7 straight positive years. The pattern has softened of late, October's last five years slipping below its longer-run record.
The takeaway is less about when to buy than what to expect: October aside, the stock's months offer little reliable tilt.
Short answers on the stock's best month (October), its worst (May), and whether it really trades seasonally.
Yes, to a moderate degree. Since 2016 its best month (October, +5.8%) has run well ahead of its worst (May, −1.3%) — the heatmap above shows how steady that gap has been year to year.
October has been the strongest, averaging +5.8% and closing higher in 8 of 10 years since 2016.
It's the weakest, averaging −1.3% — 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