Long Bonds vs S&P 500: Correlation Analysis
Pearson correlation of daily returns for 20Y+ Treasury (TLT) and S&P 500 ETF (SPY). Rolling windows, yearly breakdown, regression beta, and divergence analysis. Data window spans to (1,262 aligned observations).
What the Number Means
A correlation of 0.22 signals only a weak tendency to move together. On most days the two move independently. Do not expect one to reliably predict the other. Look for conditional relationships within specific regimes or event windows.
Recent vs Long-Run Behavior
The correlation has strengthened materially. The 90-day reading of 0.22 is 0.15 above the long-run average of 0.07. Rising correlation typically accompanies deleveraging, broad risk-off, or a dominant single-factor regime where idiosyncratic drivers get drowned out.
Statistical Details (1-Year Window)
| Pearson Correlation (r) | +0.135 |
| R-Squared (r²) | 0.018 |
| Beta (20Y+ Treasury (TLT) vs S&P 500 ETF (SPY)) | 0.111 |
| Daily Volatility σ(20Y+ Treasury (TLT)) | 0.63% |
| Daily Volatility σ(S&P 500 ETF (SPY)) | 0.77% |
| Observations | 252 |
Correlation measures directional co-movement; R² quantifies the fraction of variance explained by the linear relationship. Beta is the slope coefficient from regressing 20Y+ Treasury (TLT) returns on S&P 500 ETF (SPY) returns. A beta above 1 means the first asset amplifies moves of the second.
Year-by-Year Correlation
| Year | Correlation | Strength | Observations |
|---|---|---|---|
| 2026 | +0.220 | Weak positive | 91 |
| 2025 | +0.105 | Essentially uncorrelated | 250 |
| 2024 | +0.074 | Essentially uncorrelated | 252 |
| 2023 | +0.120 | Essentially uncorrelated | 250 |
| 2022 | +0.085 | Essentially uncorrelated | 251 |
| 2021 | -0.247 | Weak negative | 168 |
Year-by-year correlation reveals how the relationship has held up across different macro regimes. Sharp year-over-year swings in correlation often mark the transition between stress and calm periods.
Rolling 90-Day Extremes
Extremes in rolling 90-day correlation often coincide with regime changes, forced deleveraging, or the arrival of a dominant new macro theme that overwhelms normal relationships.
Methodology
Correlations are computed on daily log-adjacent returns for 20Y+ Treasury (TLT) and S&P 500 ETF (SPY), aligned on shared trading dates. We use the Pearson product-moment coefficient, which measures the linear relationship between two return series.
Windows are the most recent N observations for 30D, 90D, and 1Y (252 trading days); the 5Y figure uses all aligned data up to 1,260 observations. Beta is the OLS slope from regressing the first series on the second. Data updates daily with a 24-hour revalidation cadence.
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Get daily macro analysis on shifting correlations, regime transitions, and cross-asset signals.
Correlation is not causation and backward-looking statistics can fail when regimes shift. Positions sized on historical correlation assumptions should be stress-tested against scenarios where the relationship breaks. For informational purposes only.