As if we had any doubt after the beginning of May brought huge declines to the stock market, volatility is back in a major way. Today's market action shows just how jumpy stocks have become, with the Dow Jones Industrials (INDEX: ^DJI) falling at the open, rising in mid-morning, and falling throughout the afternoon -- only to do another late-day recovery that finished with the average up 34 points. The broader market wasn't as strong, with the Nasdaq Composite actually losing ground for the day.

Even though the Dow recovered, many Dow components did not. Cisco Systems (Nasdaq: CSCO) was the Dow's big loser today, falling nearly 2% and adding to its huge losses so far this month. With the company convinced that the overall environment for enterprise spending is holding it back, Cisco can point to results like those of NetApp as confirmation of its assessment of slowing growth throughout the industry.

Caterpillar (NYSE: CAT) lost more than 1% on the heels of more bad news about China's slowing economic growth. HSBC's purchasing managers index covering the Chinese manufacturing industry fell further into the range suggesting a contraction, sending mining companies Joy Global (NYSE: JOY) and Cliffs Natural Resources (NYSE: CLF) down sharply. Although mining is only part of Caterpillar's business, it nevertheless has been an important part of the Dow component's growth. If China doesn't reaccelerate soon, then Caterpillar could fall further from its recent highs.

Finally, JPMorgan Chase fell almost 1%. With Wall Street's major banking and investment firms taking their respective turns on the hot seat over issues ranging from questionable foreclosure practices to the mishandling of the Facebook IPO, JPMorgan still hasn't managed to push its multibillion-dollar failed trade firmly into the background. As long as JPMorgan keeps its derivative position, it will remain vulnerable to both further losses and criticism from investors.

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