Seoul: Seoul stocks surged Wednesday, led by gains in chipmakers and other big-cap tech shares, as hopes grew for a possible end to the U.S.-Iran conflict. The Korean won strengthened sharply against the U.S. dollar. The benchmark Korea Composite Stock Price Index (KOSPI) rose 426.24 points, or 8.44 percent, to 5,478.7, snapping a four-day losing streak. According to Yonhap News Agency, Wednesday's gain marked the second-largest increase ever, with the sharpest gain recorded on March 5 when the index jumped 490.36 points. Trade volume was moderate at 942.93 million shares worth 27.31 trillion won (US$18.19 billion), with winners outnumbering losers 837 to 70. Foreigners and retail investors sold a net 612.61 billion won and 3.76 trillion won worth of shares, respectively, while institutions purchased a net 4.03 trillion won worth of shares. Tracking overnight gains on Wall Street, the index opened nearly 5.5 percent higher and extended gains on solid institutional buying. The Korea Exchange (KRX), the count ry's main bourse operator, activated a five-minute buy-side sidecar about seven minutes after the opening bell, temporarily halting program-driven buy orders in KOSPI futures. A buy-side sidecar was also triggered on the tech-heavy Korea Securities Dealers Automated Quotation (KOSDAQ) market. The KOSDAQ finished at 1,116.18 by rising 6.06 percent Wednesday. The rally came after U.S. President Donald Trump said Tuesday (U.S. time) that the United States could end its military operation against Iran within "two or three weeks," adding, "All I have to do is leave Iran." Iranian President Masoud Pezeshkian also told European Council President Antonio Costa that Tehran has the "necessary will" to end the war, provided its adversaries guarantee it will not reignite, according to foreign media reports. The conflict, which began in late February following U.S.-Israeli strikes on Iran, has driven up global oil prices amid supply disruptions, rattling financial markets and fueling concerns over inflation and a potent ial economic slowdown. "The KOSPI fell 19.1 percent from its recent peak in the first week of March and could decline further. But corporate earnings remain strong, suggesting the stock market can rebound even after a significant shock," a monthly outlook report by KB Securities said. Optimism over South Korea's inclusion in the World Government Bond Index (WGBI) also boosted investor sentiment. Following its inclusion in the major global bond index managed by Britain-based index provider FTSE Russell, foreign funds tracking the WGBI are expected to flow into the local market in phases over an eight-month period through November. Big-cap tech shares led the upturn of the market. Market bellwether Samsung Electronics surged 13.4 percent to 189,600 won, while its chipmaking rival SK hynix soared 10.66 percent to 893,000 won. Top automaker Hyundai Motor jumped 9.54 percent to 488,000 won, while its sister affiliate Kia advanced 6.96 percent to 155,300 won. Leading battery maker LG Energy Solution rose 3.17 per cent to 407,000 won, and major steelmaker POSCO increased 4.06 percent to 346,000 won. Bio giant Samsung Biologics climbed 4.52 percent to 1,572,000 won, and Celltrion went up 4.46 percent to 206,000 won. Defense giant Hanwha Aerospace spiked 6.73 percent to 1,333,000 won, and nuclear power plant builder Doosan Enerbility soared 8.5 percent to 99,600 won. Major financial group KB Financial grew 4.51 percent to 148,300 won. Shipbuilders finished mixed. Leading shipbuilder HD Hyundai Heavy lost 2.9 percent to 451,500 won, while its rival Hanwha Ocean rose 5.66 percent to 127,000 won. The local currency was quoted at 1,501.3 won against the U.S. dollar as of 3:30 p.m., up 28.8 won from the previous session. Bond prices, which move inversely to yields, closed higher. The yield on three-year Treasurys fell 18.2 basis points to 3.37 percent, while the return on the benchmark five-year government bonds shed 21 basis points to 3.567 percent.