A financial data screen at Hana Bank's dealing room in central Seoul shows the Korean won quoted at 1,542.3 per dollar, shortly after daytime trading closed Friday. (Yonhap) Heavy foreign selling rattled South Korean markets on Friday, dragging the benchmark Kospi down more than 5 percent and driving the won to a 17-year low against the greenback.The Kospi closed down 5.54 percent at 8,160.59 on the day. The benchmark index opened sharply lower, tracking an overnight decline in US semiconductor stocks after Broadcom projected third-quarter AI-related revenue of $16 billion, falling short of market expectations.It fell as much as 6 percent in early trading to 8,038.1, triggering a five-minute sell-side trading curb for the 10th time this year. The index later pared some of its losses as bargain hunting stepped in and was able to close above the 8,100 mark.The US chip selloff spread to Korean technology heavyweights, sending Samsung Electronics and SK hynix down 6.4 percent and 9.92 percent, respectively, to 329,000 won and 2.07 million won ($214 and $1,344).Comments from Jensen Huang during his visit to Korea failed to boost market sentiment. While the Nvidia chief said "surprises" were being prepared for Korea, investors largely shrugged off the remarks.Shares that had recently surged on expectations of closer ties with Nvidia also retreated, with LG Electronics, LG CNS and Naver falling 7.62 percent, 7.04 percent and 4.49 percent, respectively.Offshore investors led the market downturn, dumping shares amounting to 3.52 trillion won on the main board. Institutional investors added to the pressure, net selling 943.5 billion won.Retail investors, meanwhile, stepped in as buyers, snapping up a net 4.22 trillion won worth of stocks, though the demand was insufficient to offset the broader market weakness.Massive foreign selling also weighed on the Korean won, as investors converted won-denominated proceeds into dollars.The won was quoted at 1,539.1 per dollar at the close of daytime trading, weakening by 9.4 won from the previous session. The closing marked the weakest level for the won since the 1,549 won-per-dollar closing recorded on March 9, 2009, during the global financial crisis.During the session, it hit as low as 1,549.1 per dollar, coming close to the 1,550 threshold.The secondary Kosdaq index closed down 4.5 percent, at 1,002.44. During the session, it briefly fell below the 1,000-point mark for the first time in three months since March 4.