KOSPI and the closing prices of single-stock leveraged ETFs linked to Samsung Electronics and SK hynix are displayed on an electronic board at Woori Bank's dealing room in Seoul, Wednesday. KOSPI closed at 8,228.70, up 181.19 points, or 2.25 percent, rewriting its record closing high as 16 newly listed ETF products fueled strong buying interest. Yonhap

KOSPI extended its rally Wednesday and climbed above the 8,200 level to set another high after breaching the 8,000-point mark for the first time a day earlier.

Investor sentiment was buoyed by a sharp rally in U.S. technology stocks and growing expectations surrounding the launch of single-stock leveraged exchange-traded funds (ETFs) tied to Samsung Electronics and SK hynix.

Samsung Electronics also received a boost after its wage agreement was approved in a labor union vote with 73.7 percent support. The deal eased concerns over short-term strike risks, reinforcing positive sentiment toward the tech giant's stock.

The benchmark index opened at 8,242.12, up 194.61 points, or 2.42 percent, from the previous session, and at one point surged 5 percent to 8,450.26, marking its first-ever move above the 8,400 threshold. It later pared some gains to close at 8,228.70, up 181.19 points, or 2.25 percent, rewriting its record closing high just a day after reaching the previous milestone.