The rebalance period dictates how long the stocks in a portfolio should be held. After the holding period, the stocks held in the portfolio should be sold and new stocks which have entered the screen should be purchased. Shorter term rebalancing periods may outperform nominally, but will incur higher trading costs and consume more time of the investor. Rebalancing periods can vary from microseconds to decades, depending on the style of the investor. Aikido uses the following rebalance periods – monthly, quarterly and yearly.