You are supporting an advisor review for a high-net-worth client using a Merrill investment portfolio. The client currently holds a concentrated two-asset mix and is considering adding a third asset class to improve diversification without materially reducing expected return. Your manager wants a simple quantitative explanation grounded in portfolio math, not a generic definition of diversification. Assume annual returns, standard deviation as the risk measure, and no taxes or transaction costs.
| Metric | U.S. Equity Fund | Investment-Grade Bond Fund | International Equity Fund |
|---|---|---|---|
| Expected annual return | 9.0% | 4.0% | 8.0% |
| Annual volatility | 18.0% | 6.0% | 16.0% |
| Correlation Pair | Correlation |
|---|---|
| U.S. Equity / Bond | 0.20 |
| U.S. Equity / International Equity | 0.75 |
| Bond / International Equity | 0.10 |
| Portfolio Mix | U.S. Equity | Bond | International Equity |
|---|---|---|---|
| Current portfolio | 70% | 30% | 0% |
| Proposed portfolio | 50% | 30% | 20% |
How would you quantify the diversification benefit between the current and proposed Merrill portfolio mixes, and which allocation would you recommend based on expected return relative to risk? Explain the math and the business implication for the client.