Daily research · The economy and Wall Street · written
What does Bitcoin do in the 30 days after a big S&P 500 down day?
Short answer
Across 55 cases since 2018, the typical move for Bitcoin in the 30 days after a big S&P 500 down day was +4.0%. It ended higher 64% of the time. The best 1 in 10 reached +32.5% or more, the worst 1 in 10 −25.2% or less. Not tested out of sample yet.
Typical move
+4.0%
over the next 30 days, the middle case
How often
64%
it ended higher
Best 1 in 10
+32.5%
or better
Worst 1 in 10
−25.2%
or worse
Cases
55
2018-2026, on 55 days
Higher 64% of the time against 50% on ordinary days (55 days compared): higher more often than on ordinary days.
Share on Xcopy link§ 01 · The pattern55 cases
The pattern, exactly
as of · the rule, the data, the dates
A case is the day after the S&P 500 closed 2% or more down (FRED), and the move that counts is Bitcoin's.
Each of the 55 moves is measured from the close before the event's day to the close 30 days after that day.
In our data that gives 55 measured cases on 55 separate days, from Feb 3, 2018 to Jun 6, 2026; the numbers were written on Oct 24, 2026.
§ 02 · Why it might work
Why it might work
as of · the idea traders have in mind, not a promise
When US stocks fall this hard in a day, risk is being cut across markets, and the worry is that crypto is dumped together with stocks. Traders watch whether crypto follows, shrugs it off or rebounds.
That is the reasoning behind watching S&P 500 drops; whether it held over our 55 cases since 2018 is what the next sections measure.
§ 03 · How we tested it
How we tested it
as of · our own closes, against ordinary days
- Every one of the 55 cases is measured from the close before the event's day to the close 30 days after that day, on our own daily closes (UTC).
- Each case is set against Bitcoin's own ordinary days (30-day moves starting in the 365 days before it, at least 90 of them), and 55 of the 55 days had that many to compare.
- No two cases share a day, so each of the 55 days counts once.
§ 04 · Results21 up · 16 down
Results
as of · every past case, Feb 3, 2018 to Jun 6, 2026
Of the 55 cases, 21 ended up, 16 down and 18 sideways (within ±5.5%) 30 days later; the middle case +4.0%, the average day +4.1%.
ended up (21)ended down (16)sideways, within ±5.5% (18)each line one real case · past cases, not a projection
1, 7 and 30 days against ordinary days
| After | Cases | Typical move | Typical, ordinary days | Higher | Higher, ordinary days | Against ordinary days |
|---|---|---|---|---|---|---|
| 1 day | 55 | +0.45% | +0.16% | 58% | 52% | no clear edge over ordinary days |
| 7 days | 55 | −0.03% | +0.19% | 49% | 52% | no clear edge over ordinary days |
| 30 days this post | 55 | +4.0% | +0.72% | 64% | 50% | higher more often than on ordinary days |
At the other horizons: 1 day, typical +0.45% over 55 cases; 7 days, typical −0.03% over 55 cases.
By year, the typical move ranged from −6.6% in 2019 to +18.5% in 2021; 5 of 7 years leaned the same way as the whole.
Year by year
| Year | Cases | Typical move | Higher | Lower |
|---|---|---|---|---|
| 2018 | 7 | +0.74% | 57% | 43% |
| 2019 | 5 | −6.6% | 40% | 60% |
| 2020 | 10 | +11.5% | 90% | 10% |
| 2021 | 5 | +18.5% | 60% | 40% |
| 2022 | 16 | −1.5% | 50% | 50% |
| 2023 | 1 | +12.3% | 100% | 0% |
| 2024 | 4 | +4.2% | 75% | 25% |
| 2025 | 5 | +13.3% | 80% | 20% |
| 2026 | 2 | −9.1% | 50% | 50% |
The latest 10 cases
| Day | Coin | What happened | 1 day | 7 days | 30 days |
|---|---|---|---|---|---|
| BTC | S&P 500 fell 2.6% in a day | +3.7% | +5.6% | +4.9% | |
| BTC | S&P 500 fell 2.1% in a day | +1.3% | +0.99% | −23.1% | |
| BTC | S&P 500 fell 2.7% in a day | +1.9% | −5.0% | −6.0% | |
| BTC | S&P 500 fell 2.2% in a day | +0.53% | +11.8% | +22.7% | |
| BTC | S&P 500 fell 3.5% in a day | +7.1% | +6.1% | +30.8% | |
| BTC | S&P 500 fell 4.8% in a day | +0.39% | +0.25% | +13.3% | |
| BTC | S&P 500 fell 2.7% in a day | +6.5% | +5.2% | +1.3% | |
| BTC | S&P 500 fell 2.9% in a day | −2.4% | −4.4% | +4.3% | |
| BTC | S&P 500 fell 2.1% in a day | −2.3% | −0.26% | +8.0% | |
| BTC | S&P 500 fell 3.0% in a day | +2.1% | +12.2% | +4.0% |
Source: our daily closes and our dated events, measured on .
§ 05 · Out of samplenot tested out of sample yet
Out of sample
as of · calls like it, scored on data they never saw
Not tested out of sample yet: the lab has not scored calls made from S&P 500 drops at 30 days, so the 55 cases above describe the past and are not a prediction.
§ 06 · Verdict
Verdict
as of · plain, with the caveats
In our data Bitcoin ended higher more often than on ordinary days (64% against 50% over 55 days), and both halves of the history lean the same way.
The typical move of +4.0% is small next to the spread between the best and worst 1 in 10 (−25.2% to +32.5%): single cases went either way by far more.
Calls made from S&P 500 drops have not been tested out of sample yet, so read these 55 cases as a description of the past, not a forecast.
With 55 cases, one case moves the share that ended higher by 1.8 points.
Markets change, so what S&P 500 drops did from 2018 to 2026 can stop working.
§ 07 · Questions
Questions
as of · answered from the numbers above
- How often did Bitcoin end higher in the 30 days after a big S&P 500 down day?
- In 64% of 55 cases from Feb 3, 2018 to Jun 6, 2026.
- Measured the scoreboard's way, day by day, the share higher was 64% against 50% on Bitcoin's own ordinary days.
- How big was the move over the next 30 days?
- The middle case moved +4.0% over the next 30 days.
- The best 1 in 10 reached +32.5% or more and the worst 1 in 10 −25.2% or less.
- Can you trade on this?
- Not on its own: over 55 cases it shows higher more often than on ordinary days, and it has not been tested out of sample yet.
- The +4.0% typical move is the past's, and a past pattern can stop working.
- When did it last happen?
- The latest was on Jun 6, 2026: S&P 500 fell 2.6% in a day.
- 30 days later the move was +4.9%.
- Does it depend on the year?
- No. The typical move was +18.5% in 2021 (5 cases) and −6.6% in 2019 (5 cases).