SEOUL, South Korea: South Korean chipmaker SK Hynix crossed the US$1 trillion market value mark for the first time on May 27, joining rivals Samsung Electronics and Micron Technology as booming demand for AI memory chips continues to drive record gains across the semiconductor sector.

SK Hynix shares closed 9.3 percent higher after surging as much as 14.9 percent during the trading session, lifting the company's valuation to a record 1,680 trillion won, or about $1.12 trillion.

The rally also pushed South Korea's benchmark KOSPI index to a record high during the session.

The surge follows similar milestones for Samsung Electronics earlier this month and for U.S.-based Micron Technology on May 26, highlighting how demand for artificial intelligence is reshaping the global semiconductor industry.

Strong demand for advanced memory chips used in AI systems, particularly those powering Nvidia chipsets, has tightened supply and sharply increased prices for memory semiconductors.

Industry data show memory chip prices doubled in the first quarter compared with the previous period and are expected to rise by as much as 63 percent in the current quarter as AI data center demand strains supplies used for smartphones, laptops, and automobiles.

Analysts said the supply shortage has helped major memory chipmakers post record profits.

South Korea has now become the first country outside the United States to have more than one company valued above $1 trillion. Taiwan's TSMC is the only other Asian company to have crossed the milestone.

The gains in Samsung and SK Hynix shares helped lift the KOSPI index 2.3 percent by the close after it briefly jumped more than five percent intraday, triggering a temporary halt in algorithmic trading through a market "sidecar" curb.

Together, Samsung and SK Hynix now account for roughly half of the KOSPI's total market capitalization.

The index has surged 95 percent so far this year after gaining 76 percent in 2025, making it one of the strongest-performing stock markets during the AI-driven investment boom.

"We expect memory chip demand to continue exceeding supply by 2028 to keep price levels high," said Kim Young-gun, an analyst at Mirae Asset Securities in Seoul.

Kim raised his target prices for SK Hynix and Samsung by 18.8 percent and 14.6 percent, respectively.

Samsung shares also gained after unionized workers voted to approve a tentative wage agreement, avoiding a strike that had threatened to disrupt global chip supplies.

Meanwhile, investor enthusiasm has spread to exchange-traded funds linked to semiconductor companies.

The first South Korean single-stock leveraged ETFs tied to Samsung and SK Hynix posted double-digit gains during their market debut on May 27.

"Leveraged ETF buying leads to futures buying, raising futures prices and the gap with spot prices also boosting spot purchases," said Kang Jin-hyuk, an analyst at Shinhan Securities in Seoul.

Local media reported that heavy demand briefly knocked offline the Korea Financial Investment Association website that hosts mandatory online courses for retail investors seeking to trade leveraged ETFs.