A dealer works at a dealing room in Hana Bank, Seoul, Thursday. YonhapKorean stocks opened markedly higher Thursday, led by tech gains, on rising hopes for a possible agreement between the United States and Iran to end the war in the Middle East and on Samsung Electronics' tentative wage deal with its labor union.The benchmark Korea Composite Stock Price Index (KOSPI) rose 277.42 points, or 3.85 percent, to 7,486 at the opening bell.Overnight, U.S. stocks advanced as crude oil prices declined after reports that U.S. President Donald Trump said Washington was in the "final stages" of talks with Iran.The S&P 500 rose 1.08 percent, while the Dow Jones Industrial Average gained 1.31 percent. The tech-heavy Nasdaq composite added 1.55 percent.Investor sentiment improved after Samsung Electronics reached a tentative agreement with its labor union, easing concerns over a major strike that had been scheduled to begin Thursday at the world's largest memory chipmaker.Tech shares gained as U.S. chip giant Nvidia forecast second-quarter revenue above Wall Street expectations and announced an $80 billion share repurchase program.