SK hynix to Buy Back, Cancel 40 Trillion Won in Shares; KOSPI Retakes 6,800

* Editor's note: AI PRISM (Personalized Report & Insight Summarizing Media) is an AI-based personalized news recommendation and summary service developed with support from the Korea Press Foundation. It selects and provides six tailored news items for each reader type.

1. KOSPI Soars as SK hynix Wins Praise for Record Shareholder Returns

- Key summary: The KOSPI closed at 6,852.58 on the 20th, up 381.41 points (5.89%) from the previous session, retaking the 6,800 level. The rebound was led by SK hynix's announcement the previous day that it would buy back and cancel its entire 40 trillion won in treasury stock within the next three months and return more than 50% of its cumulative free cash flow (FCF — the cash a company has left after spending on investments and other outlays) from 2025 to 2027. As a result, SK hynix ended up 12.73% at 1.691 million won, while Samsung Electronics rose 9.49% to 271,000 won. Foreign investors made net purchases of 1.7116 trillion won in the KOSPI market that day. Net buying since the 11th has reached 6.391 trillion won.

2. Personalized Cancer Vaccine Succeeds in World's First Phase 3 Trial

- Key summary: A personalized cancer vaccine, intismeran autogene, jointly developed by the U.S. firms Moderna and Merck (MSD), was administered together with the immunotherapy drug Keytruda in a Phase 3 trial of 1,137 high-risk melanoma patients, significantly lengthening the time to recurrence compared with Keytruda alone. It is the first time a messenger RNA (mRNA — genetic material that carries instructions for designing proteins)-based therapy has demonstrated efficacy in cancer treatment, beyond infectious diseases. The two companies are also conducting nine follow-up trials across six cancer types, including lung and bladder cancers, and are in talks with regulators on filing procedures with the goal of market approval in 2027. On news of the trial's success, Moderna shares surged 177% from the previous day to close at $174.38 — the largest single-day gain among S&P 500 constituents in the past 25 years. Merck also rose 12.6% to $152.20, setting a new record high.

3. U.S. Debt Tops $40 Trillion; High Rates Still Seen Despite Doubled Buybacks

- Key summary: The U.S. national debt topped $40 trillion for the first time. According to the U.S. Treasury on the 19th local time, the debt stood at $40.047 trillion as of the previous day, with $3 trillion added over the past year alone. Interest costs for this fiscal year (October 2025 to September 2026) reached $1.17 trillion, becoming the third-largest item in the federal budget. The Treasury will double the size of its Treasury bond buybacks to $4 billion per operation from next month through November, but the market continues to note that it will be difficult to prevent rising bond yields without fundamental fiscal tightening.

4. Amid Delistings of Outperformers, Active ETF Deregulation Put on Hold

- Key summary: Financial regulators have decided not to ease correlation-coefficient rules for active ETFs. Under Article 116 of the securities market listing rules, active ETFs must maintain a correlation coefficient (a figure showing how closely they move with a benchmark index) of at least 0.7 with their benchmark, and are delisted if they fall short for three months or longer. Authorities judged that allowing exceptions would leave products with returns far below their benchmark unmanaged, increasing potential harm to investors. Still, industry complaints have surfaced after four active ETFs from Korea Investment Management were delisted last month and TIME US Dividend Dow Jones Active from Timefolio Asset Management this month, even though they had outperformed their benchmarks.

5. Korean-Style Top-10 Strategy ETFs Make U.S. Debut

- Key summary: ETFs reflecting a top-10 strategy — concentrated investment in the 10 companies representing each field — have appeared on the U.S. market for the first time. Amplify, a U.S. ETF specialist manager, launched four Amplify Top-10 ETFs based on four fields — quantum computing, space, robotics and Asian memory chips — with Samsung Asset Management participating as sub-adviser and handling portfolio allocation. The Asian memory product has the highest weightings in Korean chipmakers, including Samsung Electronics (22.29%) and SK hynix (21.10%). The industry views this as a case of "reverse exporting" Korea's ETF investment culture, given that the concentrated-investment strategy long used mainly by domestic managers has expanded to the U.S.

6. The Paradox of the KOSPI Surge: Net External Financial Assets Hit 12-Year Low at $64 Billion

- Key summary: Net external financial assets stood at $64 billion at the end of the second quarter this year, down $689.5 billion from the previous quarter. According to the international investment position for the second quarter of 2026 released by the Bank of Korea on the 20th, this marks the largest decline since the statistics began in 1994 and the lowest level since the balance turned positive in the third quarter of 2014. The drop was driven largely not by a decrease in overseas assets but by the KOSPI's 67.8% surge, which swelled foreign holdings of equity securities to $1.8806 trillion. The Bank of Korea explained that net external claims remain stable and external payment capacity is sound, but a further slide in its International Monetary Fund (IMF) ranking appears unavoidable.