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 Where Is the Market Headed? We all know the stock market can be unpredictable. We all want to know, “What’s next for the financial markets?” Looking to Improve Your Financial Future? Consolidating financial accounts onto one platform can help you spell out a clearer financial future. From Boats to Brokers From the Dutch East India Company to Wall Street, the stock market has a long and storied history.