America’s AI bubble is starting to look like a Ponzi scheme. Artificial intelligence companies increasingly rely on a data centre boom that allows them to raise more money from debt markets. But the midterm elections have swept in state governments sceptical of a mass data-centre buildout. Without the data centres to raise debt, chips don’t ship and the circular financing among AI companies might face a short circuit. Market bubbles grow out of excessive investor optimism, which can accelerate...