The Dow industrials tumbled more than 1,500 points at one juncture Monday, the worst intraday fall in market history.The Dow had soared more than 40 percent since President Donald Trump's election, a period that included an impressive nearly 20 percent rise in the S&P 500 for 2017 and the fastest start ever to a year in 2018.CNBC

"The market simply did not take into account that you can't go up like this that long," Yoshikami said.

"I think there are two bubbles. We have a stock market bubble and we have a bond market bubble,I think [at] the end of the day the bond market bubble will eventually be the critical issue."The former Federal Reserve chairman predicted a rise in interest rates and fretted over the national debt and budget deficit. Dr Alan Greenspan