Portfolio Overlap Calculator
Paste two portfolios. See how much they actually overlap. Useful when you hold multiple strategies and want to know if you are diversifying or doubling up on the same tickers.
One ticker and weight per line (e.g. SPY 60). Weights can be %, decimals, or any unit; the tool normalizes to 100%.
Same format. Order does not matter. Duplicate tickers keep the first row.
Moderate overlap. Some shared exposure but each portfolio also brings distinct names.
| Ticker | Portfolio A | Portfolio B | Shared |
|---|---|---|---|
| SPY | 60.0% | 20.0% | 20.0% |
| GLD | 10.0% | 15.0% | 10.0% |
| VTI | — | 40.0% | — |
| AGG | 30.0% | — | — |
| TLT | — | 25.0% | — |
What does the overlap percentage mean?
The weight-overlap formula sums the smaller of the two weights for every ticker that appears in both portfolios: overlap = sum of min(weight_A, weight_B) per ticker. The result ranges from 0% (no shared tickers) to 100% (the portfolios are identical).
A useful rule of thumb: above ~70% the two portfolios are effectively interchangeable from a diversification standpoint. Between 30% and 70% they share significant exposure but each brings distinct names. Below 30% they are mostly independent.
This tool does not measure correlation, just weight overlap. Two portfolios with zero ticker overlap can still be highly correlated if both hold large-cap US equities through different ETFs (SPY vs VTI vs VOO). For full correlation analysis BestFolio Pro includes a correlation matrix view across all strategies.
BestFolio offers 50+ backtested portfolio strategies with monthly rebalancing signals. Build, blend, and backtest your own portfolio with full transaction-cost modeling.
Past performance is not indicative of future results. Overlap is a diversification metric, not a return forecast. Always do your own research before investing.