South Korean shares opened lower Thursday as investor sentiment worsened over the country's biggest economic contraction in the second quarter in over two decades.

The benchmark Korea Composite Stock Price Index (KOSPI) fell 8.99 points, or 0.40 percent, to 2,219.67 in the first 15 minutes of trading.

In the April-June period, South Korea's real gross domestic product (GDP) shrank 2.9 percent from the same period last year, marking the slowest growth since a 3.8 percent on-year contraction in the last three months of 1998, according to advance data from the Bank of Korea (BOK).

The quarterly GDP growth fell deeper than the BOK's earlier projection of a 2 percent on-year contraction.

Most large caps traded mixed.

Market bellwether Samsung Electronics lost 0.91 percent, while No. 2 chipmaker SK hynix climbed 0.36 percent.

Top pharmaceutical firm Samsung BioLogics slid 0.13 percent, but leading chemical maker LG Chem advanced 0.38 percent.

The country's largest automaker Hyundai Motor gained 0.84 percent, while top steelmaker POSCO retreated 0.76 percent.

The local currency was trading at 1,199.95 won against the US dollar, down 3.75 won from the previous session's close. (Yonhap)