The takeaway
iShares National Muni Bond ETF shows a slight seasonal lean over 10 years of data — strongest in November (+1.1%) and softest in October (−0.4%).
Right now
In July, the fund has risen 70% of years, averaging +0.7%, roughly 1.5 pts behind the S&P 500.
The full picture
iShares National Muni Bond ETF's most dependable month has been November, higher in 8 of 10 years; October has been its least reliable, up just 30% of the time.
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Month by month
Across the year the fund has stayed close to the S&P 500 — no single month stands out as a real edge.
“vs S&P” is iShares National Muni Bond ETF’s average for a month minus the S&P 500’s average for that same month — isolating iShares National Muni Bond ETF’s own seasonal edge from broad market drift.
Reality check
Over the last 5 years, November has closed higher 100% of the time versus 80% across the last 10 years — the pattern is strengthening.
Figures are the typical (median) November 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
This is a fund you can almost set a calendar by, and November is the anchor — it has closed higher in 8 of 10 Novembers, the steadiest beat on its year.
The strength looks broad-based rather than freakish: its average (+1.1%) and median (+1.0%) sit close together, so no single blow-out year is flattering the figure. Few peers keep such company in November — the typical stock clears it just 62% of the time.
November anchors a run, too: the November-through-January window has been the fund's reliable season. At the other end of the calendar, October is the year's quietest corner, essentially flat on average, and the edge isn't year-round — the fund has trailed the S&P 500 in April, July, and October.
November has now closed higher 8 years running. If anything it has sharpened recently — the last five Novembers run ahead of the earlier years.
For a fund this dependable in November, the sharper question is the rest of the year — outside its strong stretch, the calendar gives far less to lean on.
Short answers on the fund's best month (November), its worst (October), and whether it really trades seasonally.
Only mildly. The fund's months are fairly even — November is the firmest (+1.1%) and October the softest (−0.4%), a narrow spread that points to weak seasonality rather than a strong calendar effect.
November has been the strongest, averaging +1.1% and closing higher in 8 of 10 years since 2016.
It's the weakest, averaging −0.4% — 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.
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