The takeaway
Invesco National AMT-Free Municipal Bond ETF shows a slight seasonal lean over 10 years of data — strongest in May (+1.1%) and softest in September (−0.6%).
Right now
In July, the fund has risen 80% of years, averaging +0.8%, roughly 1.4 pts behind the S&P 500.
The full picture
Invesco National AMT-Free Municipal Bond ETF's most dependable month has been May, higher in 9 of 10 years; September has been its least reliable, up just 20% 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 Invesco National AMT-Free Municipal Bond ETF’s average for a month minus the S&P 500’s average for that same month — isolating Invesco National AMT-Free Municipal Bond ETF’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.
Its average (+1.1%) and median (+1.2%) land within a hair of each other — the tell of steady, year-after-year gains rather than one outlier doing the work. Set against the S&P 500, mind, May is close to a wash — the gain mirrors the market more than it beats it. 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 — May–July forms a firm stretch that carries much of the year. On the other side of the ledger, September has been the soft spot — the weakest of 2 months that average a loss (−0.6%), and the edge isn't year-round — the fund has trailed the S&P 500 in April, October, and March.
A long streak recently broke — May had risen 9 years straight before a −1.2% 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: May aside, the fund's months offer little reliable tilt.
Short answers on the fund's best month (May), its worst (September), and whether it really trades seasonally.
Only mildly. The fund's months are fairly even — May is the firmest (+1.1%) and September the softest (−0.6%), a narrow spread that points to weak seasonality rather than a strong calendar effect.
May has been the strongest, averaging +1.1% and closing higher in 9 of 10 years since 2016.
It's the weakest, averaging −0.6% — 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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