Although we don't believe in timing the market or panicking over daily movements, we do like to keep an eye on market changes -- just in case they're material to our investing thesis.

The Dow Jones Industrials (DJINDICES:^DJI) broke its string of six winning weeks today, with today's drop of 73 points bringing the average's total losses to more than 1.5% for the week. Given that the Dow has moved nearly straight upward without any major pullbacks since last November, investors predictably worried about fears of a possible correction, as they contemplate the uncharted territory of the coming reining-in of quantitative easing from the Federal Reserve. Broader market measures fell somewhat more modestly, with bond prices rising slightly, and oil and gold posting gains.

But among the Dow's components, signs of life came from areas that had been particularly weak. Alcoa (NYSE:AA) was the biggest gainer in the Dow, soaring almost 4% after a second-straight day of positive economic news from China. After reporting solid trade data yesterday, China said that growth in industrial production was better than expected, as well. With particular demand for imported copper, Alcoa shareholders clearly hope that respite from the long declines in the aluminum market might finally be near.

Caterpillar (NYSE:CAT), which has also moved in tandem with China's economic prospects, posted more modest gains of two-thirds of a percent. Arguably, the Chinese news was even better for the heavy-machinery giant than for Alcoa, as Caterpillar has not only gotten hurt by weak commodities prices, but also from a general lack of activity in both the construction and mining industries. Yet, one reason Caterpillar's smaller gains make sense is that while Alcoa can benefit almost immediately from higher prices, Caterpillar's customers will need to see sustained improvement before they make big capital expenditures, forcing the machinery maker to wait for second-order effects of a Chinese recovery.

Meanwhile, within China, popular stocks performed well. Baidu (NASDAQ:BIDU) added to its gains of about 50% over the past month, with an analyst upgrade helping push the search giant's stock up another 2% today. For now, Baidu retains its leadership advantage in the Chinese Internet industry, but rising competition from SINA (NASDAQ:SINA) Weibo and its partnership with e-commerce giant Alibaba could bring on a future battle for supremacy within the space sooner rather than later. SINA also climbed 2%, showing that China's Internet growth story is still big enough for everyone to benefit -- at least for now.