Korean stocks traded 1.04 percent lower late Thursday morning as investors were unnerved by concerns over the eurozone debt crisis and the local market's "quadruple witching," analysts said.

Extending earlier losses, the benchmark Korea Composite Stock Price Index (KOSPI) lost 20.00 points to 1,899.42 as of 11:20 a.m.

Quadruple witching refers to a quarterly event in which contracts for stock index futures, stock index options, stock options and stock futures expire simultaneously. In South Korea, this occurs on the second Thursday of the month ending each quarter.

Large caps fell across the board, with top steelmaker POSCO and the largest automaker Hyundai Motor shedding around 2 percent.
The local currency was changing hands at 1,131.70 won, down 6.1 won from Wednesday's close, after the central bank froze its key rate at 3.25 percent for the sixth consecutive month. (Yonhap)