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Bank of America's "Bull & Bear" indicator showed sentiment climbed on a 1-10 scale to 7.1 last week from 6.7 on December 17.
This prompted Bank of America's chief investment strategist, Michael Hartnett, to say in a January 7 note that investors were rationalizing "increasingly irrational price action on Wall St."
Hartnett laid out six warning signs to watch that could signal a bear market is beginning.
Investor sentiment has climbed from rock bottom in March to what is now approaching extremes on the other end of the spectrum — and it's starting to worry Bank of America's top strategist.