Is This the Start of a Trend Reversal?

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The problem for stocks now is simple: the market has been in an uptrend all year...until we have had two big down days...two days with selling on heavy volume....two days with roughly 90 percent of the volume at the NYSE floor to the downside.

That is calling into question whether there still is an uptrend in the stock market...that's relevant because trend followers are an important part of the market and if they determine there is no more upside to the market...the uptrend could become a downtrend.

It was another whipsaw day for stocks...that started ugly right off the bat. The problem: key commodities like copper, aluminum and nickel were again dropping, sitting at essentially 52-week lows, all on concerns about slowing global growth.

Key commodity stocks like Freeport-McMoRan (FCX), Cliffs Natural Resources (CLF), U.S. Steel (X), and Peabody Energy (BTU) all hit 52-week lows as well.

And while commodity stocks like materials and energy suffered, there were also notable declines in Industrials, and in Financials as Bank of America (BAC) missed earnings estimates, and in technology bellwether Apple (AAPL) hit a new 52-week low on concerns over slowing iPhone and iPad sales.

The markets staged a modest comeback midday,likely on word that progress was being made in the Boston Marathon bombing investigation...but faded going into the close.

By CNBC's Bob Pisani

  • Bob Pisani

    A CNBC reporter since 1990, Bob Pisani covers Wall Street from the floor of the New York Stock Exchange.

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