KOSPI surged 3.56 percent Thursday, extending its winning streak to four sessions as sharp gains in semiconductor heavyweights kept the index in positive territory. The benchmark KOSPI closed at 6,813.34, up 3.56 percent from the previous session. The index opened 2.96 percent higher and extended its gains throughout the session. Foreign and institutional investors bought a net 2.1 trillion won ($1.47 billion) and 680.9 billion won worth of shares, respectively. Retail investors, however, sold a net 2.73 trillion won worth of shares amid profit-taking. An overnight rally in U.S. semiconductor stocks spilled over into the Korean chip sector, boosting investor sentiment. SK hynix rose 5.92 percent to close at 1,593,000 won, while Samsung Electronics gained 4.89 percent to finish at 268,000 won. Samsung Electro-Mechanics also rallied after Morgan Stanley replaced Samsung Electronics with the company as its top pick and raised its target price to 2.62 million won from 2.56 million won. Shares jumped 12.58 percent to close at 1,503,000 won. Foreign investors' net selling pressure has eased con