The Rule of 72 Do you know how long it may take for your investments to double in value? The Rule of 72 is a quick way to figure it out. Share | Related Content From Boats to Brokers From the Dutch East India Company to Wall Street, the stock market has a long and storied history. Earnings for All Seasons Earnings season can move markets. What is it and why is it important? Keys to Investing for Retirement There are some key concepts to understand when investing for retirement.