The takeaway
iShares Bitcoin Trust shows a pronounced seasonal pattern over 2 years of data — strongest in May (+13.6%) and softest in August (−5.9%).
Right now
In July, the fund has risen 100% of years, averaging +7.1%, about +4.9 pts better than the S&P 500.
The full picture
iShares Bitcoin Trust's most dependable month has been May, higher in 2 of 2 years; August has been its least reliable, up just 0% of the time.
| Year | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Win rate % | ||||||||||||
| Median return % | ||||||||||||
| 2025 | ||||||||||||
| 2024 |
Month by month
The fund's clearest edge over the S&P 500 lands in February (+14.0 pts); it has trailed the market most in August (−6.2 pts).
“vs S&P” is iShares Bitcoin Trust’s average for a month minus the S&P 500’s average for that same month — isolating iShares Bitcoin Trust’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 2 years versus the last 2(the heatmap’s default window). This verdict stays anchored to that 2-year window even if you zoom the chart, so it never disagrees with the badges above.
In plain English
The seasonal story is really one month's story — May. It has closed higher in all 2 Mays, a concentration the rest of the calendar can't touch.
The strength looks broad-based rather than freakish: its average (+13.6%) and median (+13.6%) sit close together, so no single blow-out year is flattering the figure. Better still, that strength is the fund's own and not just a buoyant market — May has outpaced the S&P 500 by +12.9 points on average. Few peers keep such company in May — the typical stock clears it just 55% of the time.
It doesn't stand entirely alone — July and September have leaned firm as well, if less emphatically. At the other end of the calendar, August has been the soft spot — the weakest of 4 months that average a loss (−5.9%), and the edge isn't year-round — the fund has trailed the S&P 500 in August, June, and April. Its roughest month on record was a −16.8% February in 2025 — a reminder of how hard even a seasonal name can fall.
For a fund this dependable in May, the sharper question is the rest of the year — outside its strong stretch, the calendar gives far less to lean on. With a short 2-year record, the signal is best held loosely.
Short answers on the fund's best month (May), its worst (August), and whether it really trades seasonally.
Yes, to a pronounced degree. Since 2024 its best month (May, +13.6%) has run well ahead of its worst (August, −5.9%) — the heatmap above shows how steady that gap has been year to year.
May has been the strongest, averaging +13.6% and closing higher in all 2 years on record since 2024.
It's the weakest, averaging −5.9% — 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