Investors are warning that lofty U.S. stock markets have not yet priced in the risk of rocketing inflation and are vulnerable to a sharp spike in bond yields. Equity markets have been propelled by robust first-quarter earnings and expectations of boosts from artificial intelligence, overshadowing the risk of high energy prices and the lack of a conclusion to the war with Iran. But a spike in bond market yields over the past week - which took the 30-year Treasury bond above 5% and benchmark 10-year bonds above 4.5% - could change the picture for investors. That caused stock market caution on Friday. Paul Karger, co-founder and managing partner of TwinFocus, who manages money for ultra-high net worth families, said his clients are bombarding him with questions every time he meets with them about how to make sense of the apparent market paradox.