SK hynix shares surged to their daily upper limit on Friday, as South Korean chipmakers extended a sharp rebound following a recent market rout.

The stock jumped 29.95 percent to 1,718,000 won ($1,203) in afternoon trading on the Kospi, briefly touching the 30 percent ceiling after opening 28.37 percent higher.

South Korea limits daily stock-price movements to 30 percent in either direction, a threshold the Korea Exchange raised from 15 percent in June 2015.

The rally came a day after SK Group Chairman Chey Tae-won disclosed his first direct purchase of the chipmaker's shares. Chey acquired 3,620 shares on the open market, a transaction worth approximately 4.79 billion won based on Thursday's closing price.

Samsung Electronics also climbed 25.6 percent to 260,000 won. The broader market surge was strong enough to trigger buy-side trading curbs on both the Kospi and Kosdaq shortly after the opening bell.

The rebound followed heavy selling in recent sessions, even as the country's two largest memory-chip makers reported record earnings. Investors had been locking in profits and reassessing whether the AI-driven memory cycle was approaching a peak. SK hynix has been a primary supplier of high-bandwidth memory (HBM) chips used in AI accelerators, making its shares especially sensitive to shifts in expectations around AI infrastructure demand.

Sentiment turned more favorable after Microsoft released better-than-expected quarterly results on Thursday, alleviating concerns about the durability of artificial intelligence infrastructure spending and reigniting demand for Korean memory-chip stocks. As a major purchaser of AI-grade semiconductors, Microsoft's results served as a proxy for the health of data-center buildouts that underpin memory-chip demand.

Separately, the chip rally helped lift the Kospi nearly 17 percent on Friday morning, pushing the index almost 1,000 points higher and back above the 6,500 threshold.