Tech-heavy Nasdaq falls 2.6 percent as debate rages over whether AI is a bubble. US tech stocks have dropped sharply amid market jitters over the sustainability of companies’ enormous capital investments in AI. The Nasdaq Composite, which is dominated by tech firms linked to the AI boom, fell 2.6 percent on Thursday, its steepest fall since the index tumbled 4.2 percent on June 5. The broader S&P 500 slid 1.21 percent, the benchmark’s biggest drop since a 1.52 percent decline on July 29.