The US stock market has had a very strong run for most of the last four years. The Dow Jones Industrial Average, S&P 500 and Nasdaq Composite have all reached several new highs during this period. The recent rally to the rapid growth of artificial intelligence (AI) and spending on AI infrastructure. Margin debt hits $1.5 trillion, raising a stock market crash warning as investor risk soars. Here is what FINRA data and past market crashes show. | Business News
