Portfolio rebalancing is the process of changing the investment mix in a portfolio back to levels that represent your risk tolerance.  Over time, without portfolio rebalancing, your portfolio mix can shift as certain asset classes outperform others.  Sherman Asset Management uses portfolio rebalancing to ensure that your portfolio stays aligned with your risk tolerance.  Rebalancing can also be beneficial for managing risk during periods of volatile fluctuations in the financial markets.  To see an example please refer to this article from Forbes: Does portfolio rebalancing work?