Asset Allocation Mental Models

Asset allocation—dividing capital across stocks, bonds, real estate, cash—determines roughly 90% of portfolio return variation (Brinson, Hood, Beebower). Key sub-models: risk-return tradeoff (higher returns require higher volatility), correlation matters more than individual performance (uncorrelated assets reduce risk without proportionally reducing returns), rebalancing is systematic contrarianism (selling winners, buying losers), and age-in-bonds as starting heuristic. The core insight: allocation decisions (stocks vs. bonds) matter far more than security selection (which stocks).

When to use it

When building or reviewing an investment portfolio. When tempted to research individual stocks instead of allocation. When market volatility causes anxiety. When evaluating a financial advisor's recommendations.

How it can help

This eliminates the most common investor mistake: spending hours researching individual stocks while ignoring allocation, which determines 90% of outcomes. The framework is simple: determine allocation based on time horizon and risk tolerance, implement with low-cost index funds, rebalance annually. This outperforms most active strategies. For entrepreneurs, the equivalent is business capital allocation: how you divide resources between growth, maintenance, and reserves matters more than any individual spending decision.