Seoul shares opened lower Friday after overnight losses on Wall Street, as rising US Treasury yields and higher oil prices weakened investor sentiment. The Korea Composite Stock Price Index opened down 1.35% and had trimmed its decline to 21.05 points, or 0.31%, at 6,831.53 as of 9:15 a.m. US Treasury yields resumed their upward trend Thursday after the US Treasury announced an expanded bond buyback, reversing much of the previous day’s decline.