Asia stocks mark time before Yellen speech; dollar firm

Asian stocks edged higher on Thursday but clung to recent well-worn trading ranges while the greenback held firm against regional currencies ahead of a speech by Federal Reserve Chair Janet Yellen at a global central bankers' meeting. MSCI's broadest index of Asia-Pacific shares outside Japan edged 0.2 percent higher. Japan's Nikkei was down 0.3 percent, pressured by losses on Wall Street overnight and investor caution ahead of Yellen's speech in Jackson Hole, Wyoming, on Friday.