CNBC Daily Open: Chipping away at the AI boom

A Korea Exchange (KRX) employee monitors stock market data on trading screens inside the Korea Exchange (KRX) in Yeouido, Seoul, South Korea, on July 15, 2026. Chris Jung | Nurphoto | Getty ImagesHello, this is Leonie Kidd coming to you from London. Another day, another circuit breaker triggered. The Nasdaq-South Korea feedback loop continues to link the AI trade from one side of the globe to the other, and today it's to the downside. Read on!What you need to know todayThe velocity of the AI sell-off is increasing. Tuesday's trading in Asia saw Samsung and SK Hynix plunge, driving a 10% drop on South Korea's Kospi. The index has now fallen around 45% from its June highs. Circuit breakers were triggered once again, and contagion across the region saw steep declines for the Nikkei, led by the big tech names. The catalyst? Hard to pinpoint. During Monday's session on Wall Street, Nvidia came under selling pressure after CNBC confirmed the group is in talks with OpenAI to provide a $250 billion backstop to fund its AI infrastructure plans. The story sent Nvidia shares down over 5%, pushing its market cap just below $4.8 trillion. This allowed Apple to regain its crown as the world's mo...