The takeaway
Schwab Short-Term U.S. Treasury ETF shows a slight seasonal lean over 10 years of data — strongest in March (+0.3%) and softest in September (−0.1%).
Right now
In July, the fund has risen 70% of years, averaging +0.2%, roughly 1.9 pts behind the S&P 500.
The full picture
Schwab Short-Term U.S. Treasury ETF's most dependable month has been March, higher in 8 of 10 years; September 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 Schwab Short-Term U.S. Treasury ETF’s average for a month minus the S&P 500’s average for that same month — isolating Schwab Short-Term U.S. Treasury ETF’s own seasonal edge from broad market drift.
Reality check
Over the last 5 years, March has closed higher 60% of the time versus 80% across the last 10 years — the pattern is weakening.
Figures are the typical (median) March 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. March stands out, higher in 8 of 10 Marches, but it heads a clutch of months that pull the year reliably upward.
Its average (+0.3%) and median (+0.2%) 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 March only about 56% of the time.
The lift is near-universal — strength runs through almost every month of the year, not one window. The weaker half of the year is plainer: September 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 November, July, and April.
The pattern has softened of late, March's last five years slipping below its longer-run record.
The takeaway is less about when to buy than what to expect: March aside, the fund's months offer little reliable tilt.
Short answers on the fund's best month (March), its worst (September), and whether it really trades seasonally.
Only mildly. The fund's months are fairly even — March is the firmest (+0.3%) and September the softest (−0.1%), a narrow spread that points to weak seasonality rather than a strong calendar effect.
March has been the strongest, averaging +0.3% and closing higher in 8 of 10 years since 2016.
It's the weakest, averaging −0.1% — 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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