Today's 90-point drop for the Dow Jones Industrials (DJINDICES:^DJI) came as investors worried about global macroeconomic issues, like the banking crisis in Cyprus, and continued weakness in economic growth in Europe and China. Although the Cyprus situation is a new development, concerns about larger economic woes affecting worldwide industrial activity have limited the gains in the stock market, and arguably prevented the S&P 500 from reaching its own all-time record high.

Today, both Alcoa (NYSE:AA) and Caterpillar (NYSE:CAT) lost ground, with Alcoa falling more than 1%, and Caterpillar posting a fractional loss. But when you look at the entire year to date, the two stocks have been the two worst performers in the Dow so far in 2013, as the only two Dow components that have suffered negative total returns.

On numerous occasions, Caterpillar has reined in optimism about its business, especially in China. Even as the U.S. economy has shown signs of improvement, the extensive high-profile construction projects that define Caterpillar's core business haven't really come back in full force, as hamstrung government budgets at the federal and local level have forced delays in taking on infrastructure maintenance and construction projects. Moreover, in China, attempts from government leaders to slow the rate of inflation have already had an impact on economic growth, and will continue to do so in the future, hurting Caterpillar's business.

Meanwhile, Alcoa has shared Caterpillar's challenge of dealing with internal competition from within China, as Chinese producers have played a major role in keeping aluminum prices depressed. U.S. companies in the solar industry have had to deal with that phenomenon before, as both First Solar (NASDAQ:FSLR) and SunPower (NASDAQ:SPWR) have endured a long malaise, as Chinese solar rivals have stayed in business despite, in some cases, having negative gross margins. Finally, a weeding-out among solar stocks has started to break the industry into winners and losers, and First Solar and SunPower look like likely survivors from the melee. Similarly, Alcoa has taken steps to emerge victorious in the long run, but as long as Chinese aluminum producers keep prices down, the short-term prospects for the industry look bleak.