"Momentum for strong earnings were weakened and there are still worries surrounding US tax reforms," said Kim Sung-hwan, an analyst at Bookook Securities, noting that an upward momentum would be difficult for some time.

Most large caps closed mixed.

Steel and chem shares closed higher, with leading steelmaker POSCO closing at 320,000 won, up 2.4 percent. LG Chem, the nation's leading chemical firm, added 1.08 percent to close at 421,500 won.

Tech shares ended bearish, with top cap Samsung Electronics closing at 2,765,000 won, down 1.18 percent. Its smaller rival LG Electronics lost 1.88 percent to 94,100 won, and LG Display, a major flat panel maker, shed 1.88 percent to 94,100 won. SK hynix, a major chipmaker, also decreased 2.2 percent to 84,700 won to end a two-day winning streak.

Auto shares ended mixed, with leading automaker Hyundai Motor adding 1.29 percent to 157,000 won. Its sister company, Kia Motors, stood unchanged at 33,150 won. Auto parts maker Hyundai Mobis inched up 0.79 percent to 255,500 won.

The local currency closed at 1,085.4 won against the greenback, up 3.7 won from the previous session's close.

The market opened at 10 a.m., one hour later than usual, and closed at 4:30 p.m., one hour later than usual, due to a nationwide college entrance exam. The test was delayed by one week after a magnitude 5.4 earthquake hit the southeastern city of Pohang last week, damaging some test sites in the city. (Yonhap)