Can GPT-6 Astra reignite the memory chip and KOSPI trade?

Shares of South Korea’s leading chipmakers surged in Seoul trading yesterday, as OpenAI’s GPT-6 Astra debut four days earlier fueled expectations that the model’s memory-intensive design would tighten high-bandwidth memory supply.

SK Hynix stands out as the most direct equity expression of the Astra demand thesis. Analysts at Goldman Sachs and Morgan Stanley estimate that more than half of the $1.3 trillion to $1.5 trillion in AI capital expenditure planned for 2027 will be channeled into memory—a projection that provides fundamental ballast for the re-rating argument favoring both Korean chipmakers.

OpenAI introduced GPT-6 Astra on September 3, describing it as its most capable and aligned model to date, with notable improvements in coding, cybersecurity, computer use, and the ability to master unfamiliar software through trial and error.

The model is being rolled out to ChatGPT Plus, Pro, Business, and Enterprise subscribers, and is also accessible via the OpenAI API, Microsoft Azure, and AWS Bedrock.

“We have set a new standard with this model,” the company said in its launch statement. Saxo Bank analysts added in a note published September 7 that “capability is still moving quickly — and that supports continued AI spending.”

The market reaction in Seoul was not purely about model quality. It came at a time when Korean chip stocks had been hit hard: SK Hynix remained roughly 48.6% below its 2026 peak, while the Philadelphia Semiconductor Index’s forward price-to-earnings multiple had fallen to below 19 times from about 29 times in June, after a U.S. momentum unwind battered the sector.

That valuation gap, combined with a fresh AI catalyst, created the conditions for a sharp short-covering move.

Underpinning the price action is a $41 billion combined buyback program from SK Hynix and Samsung, with roughly $27 billion still due to be executed by November 21, according to Korea Exchange filings.

On that front, there was an encouraging shift. Foreign investors flipped back to net buying of Korean equities in the first week of September after persistent net selling through late August, when combined foreign and institutional net sales had exceeded 13.9 trillion won since SK Hynix’s buyback started on August 20.

The reversal, if it holds, removes the pressure that had kept the Kospi pinned despite mechanical buyback support. The Nasdaq 100 and Kospi 200 have traded with more than 91% price correlation over the past two years, meaning a sustained foreign return to Korean names typically accompanies renewed risk appetite in U.S. tech.

SK Hynix has leaned on outright buybacks, while Samsung leans more toward dividends. Samsung is projected to distribute 80% of its remaining fourth-quarter return as dividends, at 9,149 won per share, according to analyst expectations.

Similarly, SK Hynix could announce a further buyback of up to 40 trillion won ($28 billion) in the fourth quarter, which would extend the mechanical support floor well beyond November, although the exact announcement date has not been confirmed.