Dollar Cost Averaging vs.Lump-Sum Investing

Let’s say you have $100,000 to invest, and you want to achieve a portfolio of 90% stocks (modeled as the S&P 500) and 10% bonds (T-Bills). But that sounds risky to you. You decide to instead invest gradually over 10 years, every month putting a little bit more in, until you finally put $90,000 into stocks.

But what if you instead put everything at once into 50% stocks and 50% bonds, and kept those 50/50 proportions for the entire 10 years instead? That would also reduce your risk. You may be surprised to find out that historically the 50/50 rebalanced portfolio actually had the same amount of volatility than the 90/10 dollar cost averaged portfolio, but with a higher average return (8.37% vs. 8.05%).