South Korea's won weakened for a second straight session on Thursday, closing at 1,342.1 per dollar in Seoul as foreign investors sold a net 3.39 trillion won (US$2.53 billion) of local shares, according to Yonhap News Agency. The selling overwhelmed a Bank of Korea report, released the same morning, showing a record US$61.46 billion current account surplus for September.

The split matters for investors across Asia. Korea's export boom is pulling in dollars at an unprecedented pace, yet the currency is now trading on equity flows rather than trade. When foreign funds leave the semiconductor names that dominate the Kospi, the won follows, whatever the trade figures say.

The onshore close was down only 0.6 won from Wednesday's 1,341.5, Yonhap reported. The pressure built after Seoul's 3:30 p.m. close. Data from Trading Economics showed the won touching 1,353 per dollar later on Thursday, a four-week low and about 0.9% below the onshore close.

Chip Selloff Drives Foreign Outflows From the Kospi

The Korea Composite Stock Price Index fell 300 points, or 5.28%, to 5,383.80 on Thursday. The Korea Exchange activated a sell-side sidecar at 10:16 a.m., halting program trading in Kospi-listed shares for five minutes, Yonhap said.

Chip stocks took the heaviest losses. Samsung Electronics dropped 7.57% to 201,500 won and SK Hynix sank 9.46% to 1.26 million won. Samsung Electro-Mechanics fell 15.34%. Institutions and individuals absorbed the foreign selling, buying a net 841.8 billion won and 2.28 trillion won of shares respectively.

Yonhap tied the selloff to concerns that the U.S. Congress taking office in January could tighten rules on artificial intelligence data centers, a risk for the companies supplying memory chips to that buildout. Kim Seok-hwan, an analyst at Mirae Asset Securities, told the agency the U.S. vote hit the Kospi by "dragging down shares within the semiconductor value chains." Markets are still weighing what the midterm elections mean for U.S. technology policy.

Thursday's outflow came on top of a run of foreign selling. Foreign investors have been net sellers of Korean stocks for seven straight months, counting November so far, The Korea Times reported on Wednesday. On Nov. 2, the won fell 9.5 won to 1,343.8 per dollar in a single session, according to a Yonhap report published by The Korea Herald, while foreign investors sold a net 374 billion won of local shares that day.

Not every sector fell. Hyundai Motor rose 3.53% and Kia gained 5.22%, while internet company Naver jumped 8.26%. Government bonds rallied: the three-year yield fell 4.5 basis points to 3.669% and the five-year yield dropped 6.8 basis points to 3.769%, Yonhap said.

Bank of Korea Reports a Record US$61.46 Billion Current Account Surplus

The trade data would normally support the won. September's current account surplus of US$61.46 billion was the largest monthly figure on record, up from US$46.11 billion in August and well above the previous high of US$49.73 billion set in June, according to Bank of Korea data reported by Yonhap. A year earlier the September surplus was US$14.22 billion.

The goods account drove the result. It posted a record US$62.75 billion surplus as exports rose 92.4% from a year earlier to US$130.72 billion, while imports climbed 29.4% to US$67.97 billion. The services account ran a US$3.35 billion deficit, wider than August's US$1.68 billion gap, on higher travel spending abroad and intellectual property payments.

For the first nine months of 2026, the surplus reached US$340.66 billion, roughly four times the US$83.89 billion of the same period last year. The third-quarter total of US$149.65 billion already exceeds the US$123.05 billion surplus for all of 2025, itself a record. The central bank said the full-year surplus should top its US$450 billion forecast, and a BOK official told Yonhap that December could bring another monthly record because of year-end seasonal effects.

The surplus has not stopped dollars from leaving through other channels. Korean residents bought US$7.09 billion of overseas securities in October, up 71.5% from September, according to Trading Economics, and these purchases remain a steady source of dollar demand in Seoul. The won's move this week shows how quickly equity outflows can outweigh that export cash: it was trading near 1,336 per dollar on Oct. 29, Trading Economics data show, before foreign reserves rose to US$443.16 billion in October.

What to Watch for the Won

The won remains far stronger than earlier in the year. It weakened past 1,500 per dollar at one point this year before rebounding into the low 1,300s, The Korea Times noted, and Trading Economics data show the dollar is still 6.65% lower against the won than a year ago.

Its near-term direction rests on whether foreign funds return to Samsung Electronics and SK Hynix. Lee Kyung-soo of Hana Securities, cited by The Korea Times, said a lasting return of foreign net buying "may be at least three months away."

The next data point is the Bank of Korea's October balance of payments early next month. The bank's official said October's surplus should be the second-largest on record, behind September's.