Rebalancing your ETF portfolio is key to maintaining your desired asset allocation and making sure you're taking advantage of the market's changes. How often you rebalance is up to you, but it's important to do it regularly. Many investors rebalance annually, but you may choose to rebalance more or less often depending on your goals and how volatile the market is. Consider your risk tolerance, investment timeline, and current market conditions when deciding how often to rebalance.