You Would Rather Be... Full Size Version Share | Have A Question About This Topic? Address Thank you! Oops! Related Contents 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. The Anatomy of an Index The S&P 500 represents a large portion of the value of the U.S. equity market, it may be worth understanding. Keys to Investing for Retirement There are some key concepts to understand when investing for retirement.