Richard Fisher, president of the Federal Reserve Bank of Dallas, on Wednesday said he was concerned about "eye-popping levels" of some stock market metrics, and said the central bank has to monitor the signs carefully to make sure another bubble isn't forming. In his speech in Mexico City, Fisher said some indicators like the price-to-projected forward earnings, price-to-sales ratios and market capitalization as a percentage of GDP, are at levels not seen since the dot-com boom of the late 1990s. He noted that margin debt is pushing up against all-time records. "We must monitor these indicators very carefully so as to ensure that the ghost of 'irrational exuberance' does not haunt us again," Fisher said. While a few Fed officials have mentioned unease about stock prices, Fisher's comments are the most pointed to date. Fisher did not spare the bond market, saying that narrow spreads between corporate and Treasury debt "reflect lower risk premia on top of already abnormally low nominal yields." Fisher is a voting member of the Fed's monetary policy committee this year. H