The takeaway
iShares CMBS ETF shows a slight seasonal lean over 10 years of data — strongest in July (+0.7%) and softest in October (−0.7%).
Right now
In July, the fund has risen 90% of years, averaging +0.7%, roughly 1.4 pts behind the S&P 500.
The full picture
iShares CMBS ETF's most dependable month has been July, higher in 9 of 10 years; October has been its least reliable, up just 20% of the time.
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Month by month
The fund's clearest edge over the S&P 500 lands in January (+1.0 pts); it has trailed the market most in November (−1.7 pts).
“vs S&P” is iShares CMBS ETF’s average for a month minus the S&P 500’s average for that same month — isolating iShares CMBS ETF’s own seasonal edge from broad market drift.
Reality check
Over the last 5 years, July has closed higher 80% of the time versus 90% across the last 10 years — the pattern is holding.
Figures are the typical (median) July 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. July stands out, higher in 9 of 10 Julys, but it heads a clutch of months that pull the year reliably upward.
Its average (+0.7%) and median (+0.6%) land within a hair of each other — the tell of steady, year-after-year gains rather than one outlier doing the work. It is among its calmest months, too, its returns swinging least from year to year (a 0.7% spread), and even its worst July in 10 years lost only 0.2% — the gentlest downside anywhere on its calendar. That consistency sets it apart from the field, where the average stock manages July only about 61% of the time.
The strength clusters rather than stands alone — March–August forms a firm stretch that carries much of the year. At the other end of the calendar, October has been the soft spot — the only month to average an outright loss (−0.7%), and the edge isn't year-round — the fund has trailed the S&P 500 in November, October, and April.
A long streak recently broke — July had risen 9 years straight before a −0.2% reading in 2025. 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: July aside, the fund's months offer little reliable tilt.
Short answers on the fund's best month (July), its worst (October), and whether it really trades seasonally.
Only mildly. The fund's months are fairly even — July is the firmest (+0.7%) and October the softest (−0.7%), a narrow spread that points to weak seasonality rather than a strong calendar effect.
July has been the strongest, averaging +0.7% and closing higher in 9 of 10 years since 2016.
It's the weakest, averaging −0.7% — 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