Week 12 Day 7: Sequence Risk in Reverse: Your Superpower During Accumulation

If you are 30 and the market crashes 30%, congratulations: every dollar you invest this year buys 43% more shares than last year. When the market recovers, those cheap shares produce outsized gains. Sequence risk is your enemy in retirement but your friend during accumulation. Young investors should welcome crashes.

This is the mirror image of sequence risk: during accumulation, bad returns early + good returns later produces more wealth than good returns early + bad returns later. Why? Because you are adding money (buying shares) throughout. Bad early returns mean you buy more shares per dollar. When returns improve later, those extra shares compound aggressively. Compare: Saver A invests $500/month for 20 years. Gets -10% for 5 years, then +15% for 15 years. Saver B invests $500/month for 20 years. Gets +15% for 15 years, then -10% for 5 years. Both achieve the same average return. But Saver A ends with roughly 20-30% more wealth because the bad years happened while they were still buying. The early losses created a larger share count that later gains multiplied. This is the mathematical justification for staying calm -- even excited -- about market drops when you are young.

The formal mechanism is the dollar-weighted return (internal rate of return) versus the time-weighted return (geometric average). Two portfolios can have identical time-weighted returns but different dollar-weighted returns depending on when cash flows occur. During accumulation with constant contributions, the dollar-weighted return exceeds the time-weighted return when poor performance happens early (because subsequent contributions are invested at lower prices and benefit disproportionately from the recovery). This is the mathematical inverse of the retirement SOR problem: contributions into declining markets act as a natural hedge. Arnott, Kalesnik, and Wu (2017) documented that for dollar-cost averaging investors, a flat or declining market in the first 10 years of investing, followed by strong returns in the final 10 years, produces terminal wealth 20-40% higher than the reverse sequence. The practical advice: if you are under 40 and the market crashes, increase contributions if you can. You are buying the sale.