Tax drag on US equity returns: taxes consume 14–17% of total nominal returns and reduce real returns from 6.2% to 4.6–4.9% annually. Tax-advantaged accounts (401k) save ~0.3% annually vs taxable brokerage. Over 30 years, this compounding difference is substantial. For a quant: after-tax returns are the relevant metric — pre-tax return comparisons overstate the benefit of high-turnover or high-yield strategies vs buy-and-hold.