The issue now is just how much more can be asked of this stock cohort at this stage. Apple gained 10% Friday after its results but Amazon failed to rise even 4% and sits below its July high. A faint hint that most of the stupendous business performance is largely in these stocks by now? The Nasdaq 100, too, has surrendered a couple percentage points of outperformance versus the firm but range-bound S&P 500 over the past few weeks.
-- Michael Santoli, CNBC