Investors, playing wait-and-see with the Fed, guessed it will continue to prop up the economy, and that sent stocks higher. Gains were broad. The only S&P 500 sector to post a loss was telecom. There was little real news and trading was light, and investors will have to keep guessing about the Fed till Wednesday, when its policy meeting ends. ‘I think the market’s a little hooked on a drug here,’ said Doug Lockwood, at Hefty Wealth Partners — suggesting it’s not rational to regard the bad news that the economy still needs stimulus as good for stocks. The market has fluctuated since May 22, when the Fed hinted it might soon reduce its aid.