Seoul shares closed 2.3 percent up earlier this week, their biggest daily percentage gain in three weeks, as STX Shipbuilding surged after buying a stake in a Norwegian ship builder, while Apple's strong results boosted tech stocks, according to a Reuters report. STX Shipbuilding Co (067250.KS) surged by the daily limit of 15 percent to $74.17 after it announced the purchase of a 39.2 percent stake in Norway's Aker Yards (AKY.OL) for $800m, a move analysts said underlined its commitment to fast expansion and would bolster networks in Europe. The benchmark Korea Composite Stock Price Index (KOSPI) (.KS11) gained 2.3 percent to 1,947.98, staging a strong rebound a day after slumping 3.4 percent to its lowest close in more than a month.