Tether (USDT) is 2.5× the size of USDC (USDC) by market capitalisation. Their daily returns move closely in opposite directions (correlation -0.76 across 58 shared trading days). USDT has been the more volatile of the two, at 1% annualised against USDC's 0%.
USDTUSDC
-0.76over 58 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 | USDT | USDC |
|---|---|---|
| Max drawdown (400d) | -0.2% | -0.3% |
| Risk-adjusted return (90d) | -0.03 | 0.05 |
| Best 30 days (past year) | — | +0.2% |
| Worst 30 days (past year) | — | -0.2% |
Relative strength over 90 days: USDC outperformed USDT by 0.0% — measured on the USDT/USDC ratio, so it holds regardless of market direction.