Bitcoin (BTC) is 5.6× the size of Ethereum (ETH) by market capitalisation. Over the past 1 year, BTC is ahead by 7.9 percentage points (ETH -34.6% against BTC -26.8%). Their daily returns move very closely together (correlation 0.91 across 399 shared trading days). ETH has been the more volatile of the two, at 62% annualised against BTC's 44%.
ETHBTC
0.91over 399 shared trading days
Measured on daily returns rather than on prices. Two assets that both simply trend upward score near 1.0 on raw prices whether or not they move together, so returns are what answer the question people mean by correlation.
| Metric | ETH | BTC |
|---|---|---|
| Max drawdown (400d) | -66.5% | -53.0% |
| Risk-adjusted return (90d) | 0.29 | 0.42 |
| Best 30 days (past year) | +34.1% | +26.8% |
| Worst 30 days (past year) | -44.6% | -32.9% |
Relative strength over 90 days: BTC outperformed ETH by 0.2% — measured on the ETH/BTC ratio, so it holds regardless of market direction.