South Korean stocks tumbled nearly 10 percent Tuesday as foreign investors dumped major semiconductor shares and other market heavyweights amid profit-taking, tracking overnight losses in U.S. technology stocks. The local currency weakened against the U.S. dollar. After choppy trading, the benchmark Korea Composite Stock Price Index (KOSPI) plunged 910.71 points, or 9.99 percent, to close at 8,203.84. The index hit an intra-day high of 9,175.45. The Korea Exchange (KRX), the bourse operator,