The takeaway
Vanguard 0-3 Month Treasury Bill ETF shows a slight seasonal lean over 1 years of data — strongest in May (+0.4%) and softest in February (+0.2%).
Right now
In July, the fund has risen 100% of years, averaging +0.3%, roughly 1.8 pts behind the S&P 500.
The full picture
Vanguard 0-3 Month Treasury Bill ETF's most dependable month has been May, higher in 1 of 1 years; February has been its least reliable, up just 100% of the time.
| Year | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Win rate % | — | |||||||||||
| Median return % | — | |||||||||||
| 2025 | — |
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 Vanguard 0-3 Month Treasury Bill ETF’s average for a month minus the S&P 500’s average for that same month — isolating Vanguard 0-3 Month Treasury Bill ETF’s own seasonal edge from broad market drift.
Reality check
Not enough recent May history to say whether the pattern still holds.
Figures are the typical (median) May return and how often it rose — the last 1 years versus the last 1(the heatmap’s default window). This verdict stays anchored to that 1-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 all 1 Mays, 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. It is also the calendar's calmest month, its returns swinging least from year to year (a 0.0% spread), and even its worst May in 1 years lost only 0.4% — the gentlest downside anywhere on its calendar. 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 lift is near-universal — strength runs through almost every month of the year, not one window. The weaker half of the year is plainer: February 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 takeaway is less about when to buy than what to expect: May aside, the fund's months offer little reliable tilt. With a short 1-year record, the signal is best held loosely.
Short answers on the fund's best month (May), its worst (February), and whether it really trades seasonally.
Only mildly. The fund's months are fairly even — May is the firmest (+0.4%) and February the softest (+0.2%), a narrow spread that points to weak seasonality rather than a strong calendar effect.
May has been the strongest, averaging +0.4% and closing higher in its one year on record since 2025.
It's the weakest month, but it has still averaged a small gain (+0.2%) — quiet rather than genuinely bad.
Explore
These names have the strongest July track records on record — a starting point for comparison.
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