South Korea's Stock Market Craters as Meta's AI Bombshell Rattles Chipmakers Worldwide

A Single Announcement Sends Seoul Into Freefall

It took one headline about Meta to shake one of the world's hottest stock markets to its core. South Korean shares tumbled more than 6% on Thursday, weighed down by a global selloff in chipmakers as Meta Platforms' plan to sell computing power raised questions over excess AI capacity. The damage was swift, severe, and deeply revealing about just how fragile the AI investment story has become.

The benchmark KOSPI fell 519.03 points, or 6.25%, to 7,784.38. The sell-off was so intense that regulators had to intervene. The Korea Exchange briefly suspended program selling by triggering a sidecar — an emergency brake designed to prevent panic trading from spiraling completely out of control.

Samsung and SK Hynix Bear the Brunt

Among index heavyweights, chipmaker Samsung Electronics fell 7.71%, while peer SK Hynix lost 9.34%. According to Bloomberg, the two chip heavyweights combined lost $290 billion in value in a single session. That's not a rounding error — that's the GDP of a mid-sized country, wiped out in hours.

The reason these two companies feel global AI sentiment so acutely comes down to what they make. At the center of the storm were Samsung and SK Hynix, companies that have invested billions in developing HBM — High Bandwidth Memory — chips, which are essential for training the large language models that power AI. When investors start doubting the AI boom, the companies supplying its most critical hardware are the first to suffer. Unlike other markets, the KOSPI is directly linked to the semiconductor cycle. When sentiment in Silicon Valley shifts, Seoul is the first to feel the shockwave.

What Meta Actually Did — and Why It Spooked Everyone

Meta Platforms is developing plans for a cloud infrastructure business that will sell access to AI computing power and models, setting up a new vector of competition with industry leaders like Amazon Web Services, Microsoft Azure, and Google Cloud. Meta, which has been rushing to secure expensive data centers, is forming a business to generate revenue from excess computing power sold to outside customers. On its face, that sounds like a business opportunity. For chipmakers, it read as something more ominous: a sign that one of the biggest buyers of AI infrastructure already has more than it needs.

Meta's capital expenditure surged to $72.2 billion in 2025, with 2026 spending guidance doubling to between $125 billion and $145 billion. As of the first quarter of this year, the company had committed $182.9 billion over the coming years to AI infrastructure. However, massive investment faces profitability challenges, as the company's AI products have been slow to deliver commercial returns. The market is now asking a pointed question: if Meta — after spending at a scale that dwarfs most nations' defense budgets — is sitting on surplus capacity, is the industry overbuilt?

A Correction or a Warning Sign?

Not everyone is convinced this is a catastrophe. Multiple Wall Street banks quickly issued reports attempting to cool market panic, arguing this is not an industry inflection point. Morgan Stanley maintained its "Overweight" rating and "Top Pick" status on Meta with a $775 price target. The broader argument from bulls is that global demand for AI computing power remains enormous and that one company's surplus doesn't rewrite the whole story.

Still, the scale of Thursday's selloff is hard to dismiss. Foreign investors pulled over $2.4 billion from the Korean market in a single day. The drop suggests that the market is moving from the "excitement" phase to the "proof" phase, where companies must demonstrate actual returns on their AI investments. Investment banks in Seoul warn that the second half of 2026 will be a period of high volatility. For chipmakers in Seoul — and investors everywhere with exposure to the AI trade — the era of easy optimism may be giving way to something harder and more demanding: results.