By John Towfighi, CNN (CNN) — Shares of Google’s parent company tumbled more than 12% on Thursday, their worst day on record — a historic single-day decline bigger than any day during the Covid-19 pandemic or 2008 financial crisis. The drop erased roughly half a trillion in Alphabet’s (GOOGL) market value, the second-largest single-day wipeout

Semiconductor stocks are leading the market’s advance amid the AI boom, with Nvidia shares jumping 9% after earnings topped expectations and Micron Technology up 220% over the past year, putting it among the S&P 500’s top 10 companies. Chip stocks have driven 37% of the S&P 500’s gains this year, and chips and hardware make up nearly 45% of the Nasdaq 100’s rise. Meanwhile, traditional tech heavyweights such as Microsoft are down about 6% from last year’s highs, underscoring a widening split inside the tech sector even as indexes climb.

Iran said the Strait of Hormuz has been closed again after shipping activity had already sharply contracted. Only 25 vessels transited on Thursday, while the number of tankers dropped to single digits on Friday. About 480 ships, including 220 oil tankers, are stranded in the Persian Gulf, with 120 fully loaded with crude and 100 empty. Mines in the central channel have left only a narrow near-shore route passable, while war-risk insurance has not been restored and restarting exports could take weeks to months.