U.S. and Korean tech stocks are now tightly linked — and that could be a worry for investors - CNBC

What the report says

CNBC reported that U.S. technology shares and South Korea’s stock market are moving more closely together as the artificial intelligence investment boom links American tech companies with Korean memory-chip suppliers. Citing Rayliant data, CNBC said the 60-day correlation between the Kospi and the Nasdaq 100 recently reached about 0.50, the strongest level since 2021.

The connection is being driven largely by Samsung Electronics and SK Hynix, which CNBC said together make up more than half of the Kospi. Analysts cited in the report said the two companies are central to the AI hardware chain because their memory chips are used in data centers run by major U.S. technology firms. CNBC also reported that demand from data centers now represents more than half of global DRAM demand, up from around 40% last year, according to Futurum Group analyst Rolf Bulk.

The report said Korean trading can give investors an early indication of sentiment toward AI-related stocks before U.S. markets open, especially when news breaks outside Wall Street hours. CNBC pointed to a recent session in which the Kospi dropped more than 8%, led by a 15% fall in SK Hynix, before the Nasdaq 100 later closed lower and several U.S. chip names also declined.

Analysts warned that the tighter relationship may reduce the diversification benefit of holding both U.S. and Korean equities. CNBC said investors are increasingly exposed to a shared risk: a potential slowdown in AI-related spending by hyperscale data-center operators. The report also noted possible future divergence due to company-specific capital spending, product differences, U.S. chip policy and competition from Chinese memory producers.