"Sell in May and go away" is a bit of Wall Street doggerel that might be worth taking seriously after this spring's stock-market run-up. Stocks often stumble as the temperature rises. That's because the big money from December dividends, year-end bonuses and April IRA contributions has already made it into the market.
Consider the record, which is pretty stunning. If you'd put $10,000 into the S&P 500 with a strict sell-in-May, buy-in-October strategy on May 1, 1950, you'd have ended 2006 with more than $600,000, according to calculations from Ned Davis Research. If you'd done the opposite, and invested every May 1 and sold every Sept. 1, you'd have $12,083. (If you'd just let it ride in a buy-and-hold strategy, you'd have $129,515, according to S&P.)
But before you start texting frantic "Sell!" messages to your broker, consider these caveats: