US stock market today: Nasdaq, S&P 500 futures tumble up to 3% as tech selloff deepens; Micron slides 7%

US stock futures pointed to a sharply lower open on 23 June with Nasdaq 100 futures tumbling 2.8% and S&P 500 futures declining 1.4%, as a deepening selloff in technology stocks spilled over into Asian markets, dragging South Koreas Kospi down 10% and triggering a circuit breaker. The rout was driven by memory-chip giant SK Hynix slowing advanced AI chip production, stoking concerns that surging AI-related data centre spending may not justify elevated valuations. Adding to the pressure, traders now price in an 88% probability of a US Fed rate hike in December, up from 61% before the recent meeting, as investors brace for a more hawkish stance under new Fed Chair Kevin Warsh, with all eyes on the PCE inflation data due Thursday and Micron's earnings for an AI demand read.