America’s bull market has entered its manic phase

For most of the past couple of years the best argument that American stocks were not in a bubble was that things simply didn’t feel manic enough. Yes, prices had soared, and yes, valuations had risen so high that shareholders’ expected future returns were looking increasingly disappointing. Yes, the odds of unexpected returns were receding as well, with more or less everyone already convinced that corporate earnings would keep rocketing up while artificial intelligence revolutionised the economy.