Mike Santoli's market notes: Hiding in big tech, mixed market action, stress on the horizon?

This is the daily notebook of Mike Santoli, CNBC's senior markets commentator, with ideas about trends, stocks and market statistics.

  • "The trend is your friend – until the end," they say. The trend now is one of investors hiding in Big Tech/secular-growth plays as the average stock stagnates.
  • There's a rational basis for all this: a scarcity of long-duration cash flows and profit growth raises the premium on those that have it; ultra-low interest rates raise the implied value of the distant future today; the winner-take-most dynamics of digital platform businesses have only accelerated in the current environment.
  • Yet even rational market patterns can get over-believed and at the margins traders can get over-excited by the momentum. Probably skirting those extremes in some parts of the Nasdaq-plex. Short-term trader sentiment is bumping against overbullish extremes, etc.