Every spring, investors begin hearing the familiar phrase, “Sell in May and go away.” The idea is simple: avoid the stock market during the summer and return in the fall. But does that strategy actually lead to better financial outcomes? The historical pattern has some basis in long-run data. The practical value has been harder to capture. Transaction costs, taxes on any realized gains, and the challenge of knowing when to get back in have frequently offset whatever seasonal effect existed. The investor who sold in May often fared worse than the one who stayed put.