It’s not clear that there’s a bubble in share prices, but...
Such milestones affect nothing and should have no psychological impact, but they do. On more foundational grounds, the most widely watched long-term stock metric is the CAPE (cyclically adjusted price/earnings) multiple, popularized by the Yale University economist Robert Shiller. Another metric, espoused by Alan Greenspan when he chaired the Federal Reserve, compares the earnings yield (the inverse of the p/e ratio) with the 10-year yield. For two decades, stocks yielded more than bonds, making asset allocation easy. There Was No Alternative to stocks. Now there is. The 10-year is yielding more. It’s not clear that there’s a bubble in share prices, although they’re certainly not cheap. There might well be a bubble in the amount people are prepared to spend on AI, in the earnings that the Magnificents make on the back of that, and in projected earnings for the future. That is where trouble could arise. John Authers Bloomberg September 30, 2025 https://www.bloomb...