How Stocks Work Full Size Verison Share | Related Content 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. Investment Challenges of the Affluent Investor Affluent investors face unique challenges when putting together an investment strategy. Make sure you keep these in mind. Keys to Investing for Retirement There are some key concepts to understand when investing for retirement.