SK Hynix ADR premium hits 51% as arbitrage stalls

SK Hynix’s American Depositary Receipts jumped 27% on Tuesday, pushing the premium over its Seoul-listed shares to 51%. The surge followed the start of related options trading on US exchanges, which gave traders in the world’s largest derivatives market easier access to the artificial intelligence memory chipmaker. Just a session earlier, the ADRs had crashed 9% alongside a broader selloff in South Korean equities.

The massive pricing gap between the US and South Korean listings stems from a temporary breakdown in arbitrage. Sanghyun Park, founder of Clepsydra Capital, noted that typical mechanisms to keep prices aligned are currently blocked. “Actual arbitrage is completely frozen because the underlying new common shares do not list in Korea until July 29, the regulatory conversion pipeline is locked tight, sourcing shares to borrow in order to short the ADR is nearly impossible,” Park said.

The chipmaker raised more than $26.5 billion earlier this month through its Nasdaq debut, pricing the ADRs at $149 before they opened at $170. SK Hynix has been a primary beneficiary of the AI boom due to its dominance in high-bandwidth memory chips used in data centres. Its Korean shares have more than tripled this year, though prior to the recent volatility, the ADR premium stood at just 3%.

Such extreme dislocations invite comparisons to previous market cycles. During the dotcom bubble, Taiwan Semiconductor Manufacturing Company saw its ADR premium surge beyond 100% over its Taiwanese shares. That gap eventually collapsed, with the premium averaging just 13% over the past five years.

On Wednesday, SK Hynix shares in Seoul rose as much as 13% in a catch-up trade following the New York gains. However, the pricing anomaly underscores a deeper structural vulnerability for South Korean equities. SK Hynix and Samsung Electronics together account for nearly half of the Kospi’s weight and have driven roughly two-thirds of the index’s gains this year.

South Korea’s Finance Minister Koo Yun-cheol said authorities would closely monitor risks that could further increase market volatility. The finance ministry attributed recent market swings to foreign and institutional profit-taking, portfolio rebalancing, and shifting AI expectations. In a statement, the ministry warned that “increasing concentration in the semiconductor sector has become a factor raising financial market volatility, with the impact of fluctuations in the chip sector on the whole stock market growing.”