SEOUL, Oct 2, 2025 (BSS/AFP) - South Korean tech giants Samsung Electronics and SK Hynix were trading at their highest in a year Thursday after announcing partnerships with OpenAI, driving the country's stock market to a record high.

Samsung Electronics, the crown jewel of South Korea's largest chaebol, was up 4.7 percent in early trade, its highest in 52 weeks and the strongest level in nearly five years.

SK Hynix, one of the world's largest memory chipmakers, was also trading more than 10 percent higher -- a one-year peak.

The rally helped drive South Korea's benchmark KOSPI index past 3,500 points for the first time in history, adding more than 70 points in morning trade.

The surge followed Wednesday's announcement that both firms had signed preliminary deals with OpenAI to provide chips and other equipment for its Stargate project, during a visit to Seoul by OpenAI chief executive Sam Altman.

OpenAI's memory demand is projected to reach up to 900,000 DRAM wafers per month, which both firms said they would help supply.

SK Hynix said the figure is more than twice the current HBM industry capacity.

Dubbed "Stargate", the OpenAI for Countries initiative was launched in June under the auspices of a drive announced by US President Donald Trump to invest up to $500 billion in AI infrastructure in the United States.

Altman also met with South Korean President Lee Jae Myung, who said the OpenAI chief had praised the country as having an industrial base "unmatched by any other," and pledged close cooperation to help it become an AI hub in the Asia-Pacific region.

On Wednesday, separate government data showed South Korea's semiconductor exports hit an all-time high, driven by booming global demand for AI chips.