Two decades ago, the very survival of South Korea's SK Hynix was under question, as the company was collapsing under its debt burden.What a reversal of fortunes it has been as SK Hynix has now become South Korea's most valuable company, by overtaking the country's beloved Samsung Electronics. Samsung's market cap is higher with preferred sharesSK Hynix has been a major beneficiacy of the high-bandwidth memory demand being driven by AI. Its shares have surged by more than 340% this year alone, and its market value is now more than Samsung and US-based Micron, its only other major competitors in the HBM market.In 2002, back when it was Hynix Semiconductor and not yet acquired by South Korea's SK Group, the company came close to being sold to Micron. With SK Hynix shares closing up another 5.6% today, the company's total market capitalization now stands at $1.35 trillion, slightly above that of Samsung Electronics. Samsung has held the top spot since 2000, so this is a monumental achievement for SK Hynix, even though the market capitalization can change rapidly based on how the stock performs. Samsung did point out in a statement that a calculation of its total market value should include the company's preferred shares. When added, as of close today, its market value stands at roughly $1.47 trillion.