Why does the textbook recommend 100% equities for a young employee? That sounds extremely aggressive.

Short answer: the "100% equities for a young employee" answer is NOT a risk-tolerance recommendation — it is a math result. When you combine HER HUMAN CAPITAL (the present value of all her future salary, which behaves like a giant bond) WITH her financial assets, her OVERALL portfolio is still mostly bond-like. To get her TOTAL-WEALTH equity exposure up to a reasonable target like 60%, the financial portion has to tilt heavily — often to 100% — toward equities.

The two-asset balance sheet

Most rules of thumb forget that human capital is the biggest asset on a young person balance sheet. Look at the full picture:

Working the math

Reading the symbols: $HC$ = human capital (PV of future earnings), $FC$ = financial capital (savings/investments), $TW = HC + FC$; $w_E^{HC}$ = equity-share of HC (0 = bond-like, 1 = equity-like); $w_E^*$ = target equity in TW; $w_E^{FC}$ = equity allocation in FC we solve for.

Target overall equity allocation in total wealth: $w_E^* = 60\%$.

Bond-like human capital: $w_E^{HC} = 0$.

Required equity allocation in financial capital:

The math says she would need $1860\%$ of her financial assets in equities to hit the total-wealth target. Obviously she cannot exceed $100\%$ without leverage. So she holds 100% equities and her OVERALL exposure is still well below $60\%$.

When the recommendation changes

The "100% equities" answer applies only when ALL FOUR conditions hold:

1. Young (HC large relative to FC)
2. Stable, bond-like income (low correlation with markets)
3. Long horizon (allows mean reversion to work)
4. Sufficient liquidity / emergency fund OUTSIDE the equity-tilted account

If ANY of these breaks (commission salesperson, weak emergency fund, short horizon), the equity tilt is reduced.

The "age in bonds" rule is the broken intuition

The classic "age in bonds" rule (60% bonds at age 60, 70% bonds at age 70) assumes you have NO human capital. That makes sense in the spending phase, when HC really is near zero. In accumulation it ignores the dominant asset.

A better rule: as you age, your HC declines, so your FC equity tilt should ALSO decline. Not because equities became riskier — but because your implicit bond exposure (HC) is shrinking.

For the full life-cycle math, see our human capital article.