While stocks are down some 14% off their April highs, GMO’s Jeremy Grantham says they are still well shy of fair value territory.

In an interview with CBS MoneyWatch, Grantham says he puts fair value for the S&P 500 somewhere between 800 and 875. (The upper bound of that range is almost 20% below where the index stood as of Wednesday afternoon.)

“There’s a veneer of confidence that’s not as thick as it looks,” Grantham said. “If you can crack confidence and knock the market down to 800, you would have cheap equities, especially outside the U.S.”

Grantham says a number of factors could push the market down toward that fair value range. Among them: more bad news from Greece, China, Korea or the Gulf of Mexico, and, of course, unforeseen circumstances that pop up.