An epic rally in mega cap tech stocks has brought major stock indexes back to all-time highs or close to it.

But most companies have yet to get in on the party. And there are signs that the tech titans have run out of room to run — as we saw when the Nasdaq dropped 2% on Thursday. Today looks like it could be just as rough.

Has economic reality finally caught up with unsustainable valuations? Or is this just a minor blip as the next long-term bull market heats up?