The Korea Composite Stock Price Index and the Korean Securities Dealers Automated Quotations are displayed at the Korea Exchange in Seoul on March 4. | Bloomberg

South Korea has leapfrogged the U.K. to become the world’s eighth-biggest stock market, fueled by a high-octane rally in its artificial intelligence-linked technology champions.

The total market capitalization of Korean-listed companies has surged more than 45% this year to $4.04 trillion, while the U.K.’s has climbed about 3% to $3.99 trillion, according to data compiled by Bloomberg. The size of the U.K. market was about double that of South Korea’s as recently as the end of 2024.

The surge in Korean stocks underscores the global pivot toward companies linked to artificial intelligence, which has driven gains in the Asian nation’s two biggest listed companies: Samsung Electronics and SK Hynix. The two memory-chip behemoths now account for more than 40% of the total market cap of the benchmark Kospi index, which has more than 800 constituents.…