South Korean stocks plummeted more than 6 percent Friday, after briefly topping the historic 8,000-point landmark, as investors moved to cash out tech and other market heavyweights after a record-breaking rally amid lingering uncertainties over the Middle East crisis. The benchmark Korea Composite Stock Price Index (KOSPI) plunged 488.23 points, or 6.12 percent, to close at 7,493.18, after rising as high as 8,046.78. The KOSPI had started marginally lower but turned higher shortly after opening,