Stock markets have turned volatile during the Thanksgiving holiday week, and that's created a rift on Wall Street. Although some major benchmarks are holding up well, the Nasdaq Composite (NASDAQINDEX:^IXIC) has been down fairly sharply for two days in a row. Just before noon ET on Tuesday, the Nasdaq was down more than 1%, bringing its two-day drop to more than 350 points.

Looking more closely within the Nasdaq, many of the up-and-coming high-growth companies that have performed so well over the past couple of years are coming under substantial pressure, with outsized declines that seem out of proportion to any fundamental news. Yet investors in those stocks have seen firsthand just how volatile they can be in producing massive returns, so it's only natural that the inevitable pullbacks these stocks experience will also be gut-wrenching in their magnitude.

Yet it's also human nature to wonder if perhaps the bull market in these high-growth Nasdaq stocks might finally have come to an end.