Investing legend Jeremy Grantham says market speculation has already peaked —and warns the S&P 500 could plunge 44% despite the Fed's best efforts

The rampant speculation in meme stocks, joke cryptocurrencies, and other questionable assets has already passed its zenith, Jeremy Grantham told Bloomberg's "Front Row" in an interview scheduled to air next week. "I think the peak of crazy behavior is behind us, I really do," the notorious doomsayer …