Tax-Loss Harvesting & Direct Indexing: Empirical After-Tax Alpha Modeling

## Direct Indexing and Empirical Tax Alpha

When an investor purchases an ETF (e.g. VOO), they hold an aggregate wrapper. Even in down markets, individual component stocks experience dispersion. Direct indexing holds the underlying 500 equities directly in a separately managed account (SMA).

### Mathematical Dispersion Benefit

Consider an index that finishes flat (+0.0%) across a calendar quarter:
- 220 companies drop between -5% and -35%.
- 280 companies rise between +4% and +40%.

In a traditional ETF, the investor harvests $0 in losses. Under algorithmic direct indexing, losses on the 220 declining stocks are harvested daily, generating deductible capital losses against ordinary income and capital gains.

```
Net Tax Alpha = Sum(Harvested Losses * Marginal Tax Rate) - Tracking Error Cost
```

| Market Volatility Regime (VIX) | Annual Loss Harvested (% of AUM) | Marginal Tax Rate (Fed+State) | Net Realized Alpha |
|:------------------------------|:--------------------------------:|:-----------------------------:|:------------------:|
| Low Volatility (VIX < 15) | 2.8% | 42% | +1.18% |
| Medium Volatility (VIX 15-25) | 4.6% | 42% | +1.93% |
| High Volatility (VIX > 25) | 7.8% | 42% | +3.28% |