Rebalancing is a risk-management rule first and a return story second. What is happening: The core function of rebalancing is to stop winners and losers from rewriting your allocation without permission. Why it matters: That matters because unmanaged drift can quietly turn a balanced portfolio into a concentrated macro expression. $$ New\ Weight_i = \frac{Target_i}{\sum Target} $$ Plain English: Rebalancing is just returning the book to the risk budget you intended. In practice: A strong equity run can make a nominally balanced book far more cyclical than the owner realizes. Watch for: The mistake is evaluating rebalancing only by whether it improved return over one recent sample. Useful lens: Before reacting, ask what mechanism would still matter here if the headline disappeared tomorrow. That is usually where the edge is: not in the vocabulary, but in the structure underneath it.