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

What: Two weeks following a rally inspired by Caterpillar's (NYSE: CAT) $900 million buyout of China's ERA Mining-Machinery, shares of heavy equipment renter RSC Holdings (NYSE: RRR) surged as much as 14% in early trading. Industry peers United Rentals (NYSE: URI) and Essex Rental also enjoyed big gains.

So what: Investors can thank Deere (NYSE: DE) for today's action. The farm and construction equipment specialist reported big fourth-quarter revenue and earnings in the run-up to the Thanksgiving holiday here in the United States.

Now what: Skeptics will rightly point out that RSC merely rents equipment made and sold by Deere and Caterpillar. But increasing sales at both companies suggests overall demand for heavy equipment, which in turn should be good news for renters. Do you agree? Would you buy shares of RSC Holdings at current prices? Please weigh in using the comments box below.

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