Japan's Nikkei 225 rose for a fifth straight session on Aug. 17, closing up 506.45 points, or 0.74%, at 69,220.25 as late buybacks in semiconductor-related shares including Kioxia Holdings and Fujikura lifted the benchmark above 69,000 despite weak breadth and a softer Topix. On Aug. 18, the rally reversed into a broader risk-off selloff: the index was down 689.20 points to 68,531.05 by 11:00 a.m. and about 1,528 yen below the previous close by 2:50 p.m., with Advantest, Tokyo Electron and Fast Retailing leading the drag as investors squared positions before a slate of U.S. economic data, even as SoftBank Group, Mitsubishi Corporation and Takeda Pharmaceutical provided some support and advancing stocks outnumbered decliners by late morning.