It Was the Best of Times, It Was the Worst of Times All about how missing the best market days (or the worst!) might affect your portfolio. 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. Required Reading: The Economic Report of the President The Economic Report of the President can help identify the forces driving — or dragging — the economy. Taxable vs. Tax-Deferred Savings Use this calculator to compare the future value of investments with different tax consequences.