The last time US stocks were this pricey relative to the debt market, the S&P 500 crashed 50%

• US stocks are near their most expensive levels in over two decades, relative to the debt market.
• The last time stocks were this pricey versus debt was during the dot-com boom - that was followed by a 50% crash in the S&P 500.
• "Equity risk premium is near its worst ever level going back to 1927," and previous such instances have triggered major market corrections, research firm MacroEdge said.

US stocks surprised much of Wall Street this year with a strong run that defied decades-high interest rates and recession calls. The rally was fueled by slower inflation and hype over artificial intelligence.