The index has almost wiped out all the gains made after markets rallied on the U.S. Federal Reserve's new QE3 job-boosting stimulus.
Australian shares .AXJO inched down 0.1 percent and South Korean shares finance/markets/index?symbol=kr%21kspi">.KS11 eased 0.4 percent.
"Foreign investors' diminishing risk appetite and increased sell orders from equity funds have weighed on the index," said Lee Sun-yup, an analyst at Shinhan Investment Corp, of the Korea Composite Stock Price Index (KOSPI).
Japan's Nikkei stock average .N225 opened down 0.6 percent to hit a fresh two-week low. .T
As protestors against severe austerity measures took to the streets and clashed with police in Spain and Greece, European equities saw their worst day in two months, while the euro hit a two-week low against the dollar and Spanish 10-year bond yields rose back above 6 percent.
Spanish 10-year yields had held below 6 percent since the European Central Bank said on September 6 it would buy sovereign bonds of euro zone states which request a bailout, aiming to trim borrowing costs.
"The recent dose of central bank support has kept broader markets well-behaved for the time being," Barclays Capital said in a note.
"The announcement of detailed stress test results, the 2013 budget, and a structural reform package from the Spanish government are expected before the end of the week. These will be crucial in determining whether the current episode intensifies or not," it said.
Spanish Prime Minister Mariano Rajoy presents his 2013 budget on Thursday, while gradually moving towards seeking a sovereign bailout, which would activate the ECB's bond-buying scheme to help calm market jitters.
On Friday, Moody's is expected to publish its latest review of Spain's credit rating. An independent audit of Spain's banks will on the same day reveal a stress test showing how much money Madrid will need from a 100 billion euro ($130 billion) aid package that Europe has already approved for the banks.
Greece's international lenders remained divided over how to approach Athens' debt restructuring as creditors seek to minimize losses on their exposure.
The euro traded at $1.2878, not far from a two-week low of $1.2835 touched on Wednesday.
The yen was at 77.67 yen, staying near a one-week high of 77.585 hit on Wednesday.
The dollar index .DXY measured against a basket of currencies eased 0.1 percent to 79.793, off a two-week high of 80.012 reached on Wednesday, which weighed on dollar-denominated industrial commodities such as oil and copper, also pressuring safe-haven gold.
As investor risk aversion grew, the CBOE Volatility index .VIX, a gauge of expected volatility in the Standard & Poor's 500 index .SPX, jumped 8.94 percent on Wednesday for its biggest daily increase in 2-1/2 weeks, after rising to a three-week high.
The Bank of Korea said on Thursday the manufacturing business outlook index for October was marginally above the outlook level in August which was the worst in three years, as companies struggled with anaemic domestic demand and rising global raw material prices.
U.S. chief executives' view of the economy deteriorated sharply in the third quarter and is now as bleak as it was in the immediate aftermath of the last recession, according to a survey released by the Business Roundtable on Wednesday.
