The core idea: every investor, regardless of risk appetite, should hold the same mix of risky assets. What differs between a conservative and an aggressive investor is only how much of that mix they hold. [2]
There is one "best" risky portfolio. Plot every possible combination of risky assets on a risk-return chart. The upper-left boundary is the Efficient Frontier — definition">efficient frontier — the best possible return for each level of risk. Among all those portfolios, one has the highest reward-per-unit-of-risk. That is the tangency portfolio. [2]
Combine it with cash. You can mix the tangency portfolio with the risk-free asset (think: liquid fund earning ~6.5%, roughly the repo rate). This blend forms a straight line called the CAL — Capital Allocation Line — definition">Capital Allocation Line (CAL):
$$E[R_C] = R_f + \frac{E[R_T] - R_f}{\sigma_T} \cdot \sigma_C$$
Every point on this line is achievable just by adjusting how much you put in cash vs. the tangency portfolio. [2]
| Common mistake | What theory says |
|---|---|
| Spend hours picking funds | Spend hours getting Asset Allocation — definition">asset allocation right first |
| Different investors need different equity funds | Everyone needs the same risky portfolio; only the amount differs |
| Chase last year's top fund | Ask whether the portfolio is on the efficient frontier |
Research (Brinson, Hood, and Beebower, 1986) shows asset allocation explains 90–95% of the variation in long-run portfolio returns — fund selection is a distant second. [2]
In practice, you cannot compute the exact tangency portfolio. But Index Fund — definition">index funds across asset classes (equity, debt, gold) are a low-cost approximation. [2] [6]
Apply this → Use the Strategic Allocation module to see how changing your equity/debt/gold weights shifts your portfolio along the efficient frontier.