Seoul stocks closed sharply lower Monday as disappointment over Samsung Electronics' shareholder return plan triggered a sell-off in semiconductors. The Korean won rose against the US dollar. The benchmark Korea Composite Stock Price Index (Kospi) dipped 215.99 points, or 3.12 percent, to 6,696.96. After opening lower, the index extended losses as large-cap tech shares came under selling pressure from foreign and institutional investors. "The Kospi was weighed down by disappointment over Samsung