FRANKFURT : The European Central Bank warned on Wednesday about a "bubble" in stocks related to artificial intelligence (AI), which could burst abruptly if investors' rosy expectations are not met. The warning came as part of the ECB's twice-yearly Financial Stability Review, a laundry list of risks ranging from wars and tariffs to cracks in the plumbing of the banking system. The central bank for the 20 countries that share the euro noted the stock market, particularly in the United States,