Correlation in Portfolios
What is it?
Correlation measures how closely two investments move in relation to each other, expressed as a value between -1 and +1. A correlation of +1 means two assets move in perfect lockstep; -1 means they move in exactly opposite directions; 0 means their movements are unrelated. Combining assets with low or negative correlation is the mechanism behind the diversification benefit described in Modern Portfolio Theory.
Why should you care?
Two funds can look diversified simply because they have different names or categories, while actually being highly correlated (moving together) and offering little real diversification benefit — understanding correlation helps distinguish genuine diversification from the illusion of it.
Real-life example
An investor holds two different large-cap equity mutual funds, believing they're diversified because they're managed by different AMCs. If both funds are highly correlated (which is common among funds in the same category, since they often hold similar large, well-known stocks), the investor's portfolio behaves similarly to holding just one large-cap fund — true diversification would require adding an asset class with meaningfully lower correlation, like debt or gold.
Common mistakes
- Assuming holding multiple funds from different AMCs automatically means diversification, without checking how correlated their underlying holdings and returns actually are.
- Ignoring that correlations between asset classes can shift during market stress — assets that appear uncorrelated in calm markets sometimes move together more closely during sharp downturns.
- Chasing negative correlation for its own sake without considering that a negatively correlated asset may also have a much lower expected return, changing the portfolio's overall return profile.
Illustrative correlation ranges between asset types (general, varies over time and market conditions)
| Asset pair | Typical correlation tendency |
|---|---|
| Two large-cap equity funds (same category) | Often highly correlated |
| Equity fund and debt fund | Typically low to moderate correlation |
| Equity fund and gold | Historically often low or occasionally negative correlation |
FAQ
Can correlation between two assets change over time?
Yes — correlation is not a fixed property; it's typically calculated over a specific historical period and can shift as market conditions, economic cycles, and the underlying businesses change.
Does India's mutual fund category system account for correlation directly?
Not explicitly — SEBI categories group funds by mandate and market-cap focus, which often correlates with (but isn't identical to) how similarly the funds actually move; two funds in the same category can still have somewhat different correlation profiles.
Why do correlations often rise during market crashes?
During periods of broad market stress, many asset classes can decline together as investors reduce risk across the board — a phenomenon sometimes described as "correlations go to 1 in a crisis," which is a known limitation of relying purely on historical correlation for diversification planning.
How does FundSageAI's overlap analysis relate to correlation?
FundSageAI's diversification overlap feature analyses category-level overlap across holdings, which is a practical, simplified proxy for correlation — funds with heavy category overlap tend to be more correlated, even without a precise statistical correlation calculation.
See this concept applied to your own portfolio
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