It’s not like the Apple bulls haven’t had a hard month, already.

Apple is down 16% from last month's record high of $644. And the slide has triggered chatter that Apple could land in bear market territory – that is a decline of 20% or more from its high.

Now -- adding insult to injury -- famed money pro Roger McNamee tells us, Apple’s best days as a stock are behind it.

“The problem with Apple, as a stock, is that it counted for more than half the return in the S&P 500 last year,” he says on CNBCs Fast Money Halftime Report. “I just don’t know how long we can count on Apple outperforming the index that it’s such a large part of.”

Also he says, Apple may be a victim of its own success.  Keep in mind, over the past 10 years, Apple has gone from about $6 to $600/share - a gain of more than 4000%.