South Korean shares retreated for six straight days on Wednesday as foreign investors kept their selling spree for the 11th consecutive session amid concerns over the Greek political turmoil that continued to weigh on the market.

The benchmark Korea Composite Stock Price Index (KOSPI) plunged 58.43 points, or 3.08 percent, to close at 1,840.53. Trading volume stood at 419.78 million shares worth 5.47 trillion won (4.7 billion U.S. dollars).

The KOSPI started lower and extended its earlier losses throughout the session as foreigners continued to dump local shares as worries over prolonged Greek political turmoil and debt woes continued to haunt the market.

Greece failed to establish a coalition government during their final talks, nine days after the parliamentary election. Investors feared that the European country will be forced to face another round of elections, raising concerns about the country's future in the currency union.

Adding to fears, Greek President Karolos Papoulias said depositors withdrew 700 million euros (898 million U.S. dollars) from local banks Monday, warning that "the strength of banks is very weak right now." "Fears spread that Greece may face default and may even be forced out of the eurozone. Greece was expected to carry out another round of general elections, but it is not necessarily seen as negative because the turn to less tightened austerity plans stemming from the re-election may help lessen the burden for Greece," Yoo Kyung-ha, an analyst at Dongbu Securities in Seoul, told Xinhua.

Yoo also noted that tech shares such as Samsung Electronics and SK Hynix suffered huge losses on rumors that Elpida Memory received big orders for semiconductor supply from Apple, saying that concerns deepened that South Korean chipmakers may suffer from reducing sales in chips due to Apple's growing dependence on other chipmakers.

Offshore investors dumped a net 500.4 billion won worth of local shares, keeping their selling spree for 11 straight sessions. It was the first time since November last year when foreigners sold local shares worth more than 500 billion won.

Retail investors and local institutions bought shares, but failed to prevent the KOSPI from falling further. Retail investors bought a net 272.7 billion won worth of shares, and institutional investors purchased a net 40.2 billion won worth of stocks.

Tech shares led the market decline on Elpida-related rumors. Market bellwether Samsung Electronics tumbled 6.18 percent to 1, 230,000 won, and memory chip giant SK Hynix plunged 8.89 percent to 23,050 won. Consumer electronics giant LG Electronics declined 4.27 percent to 67,300 won and Samsung SDI plummeted 8.08 percent to 153,500 won.

Other large-cap shares ended bearish. Top automaker Hyundai Motor retreated 4.19 percent to 240,000 won, and its affiliate Kia Motors lost 3.96 percent to 77,600 won. The nation's biggest auto parts maker Hyundai Mobis dipped 3.62 percent to 279,500 won and top steelmaker POSCO slid 2.23 percent to 372,500 won.

The local currency finished at 1,165.7 won against the greenback, down 11.6 won from Tuesday's close.

Bond prices ended mixed. The yield on the liquid three-year treasury notes closed steady at 3.38 percent, but the return on the benchmark five-year government bonds fell 0.01 percentage point to 3.49 percent.