Still, investors were cautious ahead of a speech by Federal Reserve Chair Janet Yellen later in the day at the annual gathering of central bankers in Jackson Hole, Wyoming, which will be studied for any fresh signals about the timing of U.S. Investors “want to hold their positions until Yellen’s speech is over, and they may take profits after that,” said Norihiro Fujito, a senior investment strategist at Mitsubishi UFJ Morgan Stanley Securities.