Direct Answer
The rolling correlation between stock returns and bond returns. It determines whether bonds have tended to hedge equity risk (negative correlation) or have fallen together with stocks (positive correlation). A negative correlation means bonds have offset equity losses and diversified a portfolio; a positive correlation, as in inflation-driven regimes, means bonds provided less protection.
Stock/Bond Correlation: Formula, Meaning, Signals, Examples and How to Use It
How Is Stock/Bond Correlation Calculated?
The rolling correlation between stock returns and bond returns. It determines whether bonds have tended to hedge equity risk (negative correlation) or have fallen together with stocks (positive correlation).
Formula: Correlation = covariance(stock returns, bond returns) / (st. dev. of stock returns x st. dev. of bond returns) over a rolling window
Inputs:
- Periodic stock index returns
- Periodic bond index or Treasury returns
- Rolling window length
Worked example. A covariance of 0.000012 with standard deviations of 1.1% for stocks and 0.4% for bonds gives a correlation of 0.27. The inputs are illustrative numbers, not market data.
Reading it. A negative correlation means bonds have offset equity losses and diversified a portfolio; a positive correlation, as in inflation-driven regimes, means bonds provided less protection. The sign has changed across macro regimes.
Limits. The estimate is sensitive to window length and return frequency, and past correlation can flip when the inflation or growth regime changes. It captures linear co-movement only, not tail behavior.
What is Stock/Bond Correlation?
The rolling correlation between stock returns and bond returns. It determines whether bonds have tended to hedge equity risk (negative correlation) or have fallen together with stocks (positive correlation).
How to use Stock/Bond Correlation
A negative correlation means bonds have offset equity losses and diversified a portfolio; a positive correlation, as in inflation-driven regimes, means bonds provided less protection. The sign has changed across macro regimes. A reading alone is never a buy or sell signal; it needs context from price structure, volume, volatility and the broader market regime.
Strengths
- Bounded between -1 and +1, the correlation gives a standardized reading of hedge quality that does not depend on either asset's volatility.
- A rolling window shows the sign changing over time, which reveals when bonds switched from diversifying to moving with stocks.
- Reproducible when the formula and data convention are fixed.
Weaknesses and limitations
- The result depends on which bond index is used, since Treasuries and corporate bonds carry different equity-like credit exposure.
- Correlation shows direction but not size of hedge: a modest negative value with low bond volatility offsets little equity loss.
- Correlated indicators can create false confidence by repeating the same underlying information.
Editorial and risk note
This page is educational content, not individualized investment advice. It should not imply guaranteed prediction, accuracy or outperformance.
Frequently Asked Questions
Is Stock/Bond Correlation a buy or sell signal?
No. A negative correlation means bonds have offset equity losses and diversified a portfolio; a positive correlation, as in inflation-driven regimes, means bonds provided less protection. The estimate is sensitive to window length and return frequency, and past correlation can flip when the inflation or growth regime changes. A trade built on it still needs a trigger, an invalidation rule, a position size and realistic execution assumptions.
What is the best setting for Stock/Bond Correlation?
Stock/Bond Correlation takes these inputs: periodic stock index returns; periodic bond index or Treasury returns; rolling window length. There is no universal best setting for the tunable ones, so test them across instruments, regimes and out-of-sample periods and favor stable parameter regions over one historical winner.
Can Stock/Bond Correlation be used by itself?
The estimate is sensitive to window length and return frequency, and past correlation can flip when the inflation or growth regime changes. It captures linear co-movement only, not tail behavior. For that reason it is read next to measures of direction, participation, valuation, liquidity and risk, not alone.
Does Stock/Bond Correlation work on every timeframe?
The calculation (Correlation = covariance(stock returns, bond returns) / (st. dev. of stock returns x st. dev. of bond returns) over a rolling window) can be run on any bar size, but behavior is not portable: a reading on a five-minute chart describes a very different market window from the same reading on a daily chart. Validate the exact timeframe before relying on it.
Why does Stock/Bond Correlation give false signals?
The result depends on which bond index is used, since Treasuries and corporate bonds carry different equity-like credit exposure. Correlation shows direction but not size of hedge: a modest negative value with low bond volatility offsets little equity loss. Lag, noise and regime changes add to this, because market participants react to new information after the reading is calculated.
How should Stock/Bond Correlation be backtested?
Rebuild Stock/Bond Correlation from periodic stock index returns using point-in-time data, write the rules before testing, include delisted securities where relevant, model realistic fills and costs, reserve a validation sample and compare with a simpler baseline.