The tech-heavy US Nasdaq share index is on track for its worst day in 18 months after slumping by up to 5% on Thursday amid growing signs that the artificial intelligence industry will face tougher regulation after this week’s midterm elections.

As Wall Street sustained widespread losses, the Nasdaq composite tumbled into ‘correction territory’ – more than 10% below its recent record high. The index was heading for its biggest one-day fall since Donald Trump announced his ‘liberation day’ tariffs on US trading partners in April 2025.