The takeaway
SPDR® Nuveen Bloomberg Municipal Bond ETF shows a slight seasonal lean over 10 years of data — strongest in December (+0.4%) and softest in September (−0.7%).
Right now
In July, the fund has risen 70% of years, averaging +0.8%, roughly 1.4 pts behind the S&P 500.
The full picture
SPDR® Nuveen Bloomberg Municipal Bond ETF's most dependable month has been December, higher in 8 of 10 years; September has been its least reliable, up just 20% of the time.
| Year | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Win rate % | ||||||||||||
| Median return % | ||||||||||||
| 2025 | ||||||||||||
| 2024 | ||||||||||||
| 2023 | ||||||||||||
| 2022 | ||||||||||||
| 2021 | ||||||||||||
| 2020 | ||||||||||||
| 2019 | ||||||||||||
| 2018 | ||||||||||||
| 2017 | ||||||||||||
| 2016 |
Month by month
The fund's clearest edge over the S&P 500 lands in January (+0.5 pts); it has trailed the market most in April (−1.8 pts).
“vs S&P” is SPDR® Nuveen Bloomberg Municipal Bond ETF’s average for a month minus the S&P 500’s average for that same month — isolating SPDR® Nuveen Bloomberg Municipal Bond ETF’s own seasonal edge from broad market drift.
Reality check
Over the last 5 years, December has closed higher 60% of the time versus 80% across the last 10 years — the pattern is weakening.
Figures are the typical (median) December 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. December stands out, higher in 8 of 10 Decembers, but it heads a clutch of months that pull the year reliably upward.
Its average (+0.4%) and median (+0.4%) land within a hair of each other — the tell of steady, year-after-year gains rather than one outlier doing the work. That consistency sets it apart from the field, where the average stock manages December only about 58% of the time.
The strength clusters rather than stands alone — November–January forms a firm stretch that carries much of the year. The weaker half of the year is plainer: September 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 April, October, and March.
The pattern has softened of late, December's last five years slipping below its longer-run record.
The takeaway is less about when to buy than what to expect: December aside, the fund's months offer little reliable tilt.
Short answers on the fund's best month (December), its worst (September), and whether it really trades seasonally.
Only mildly. The fund's months are fairly even — December is the firmest (+0.4%) and September the softest (−0.7%), a narrow spread that points to weak seasonality rather than a strong calendar effect.
December has been the strongest, averaging +0.4% and closing higher in 8 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