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 What Smart Investors Know Smart investors take the time to separate emotion from fact. Rebalancing Your Portfolio Over time, different investments' performances can shift a portfolio’s intent and risk profile. Rebalancing may be critical. How Compound Interest Works Use this calculator to better see the potential impact of compound interest on an asset.