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: Shares of construction equipment renter RSC Holdings (NYSE: RRR) jumped as much as 10.3% on moderately high trading volume.

So what: The construction equipment sector is jumping all over the place today on news that Caterpillar (NYSE: CAT) is buying Chinese operator ERA Mining-Machinery in a $900 million deal. Mining-gear builder NACCO Industries (NYSE: NC) and direct RSC rival United Rentals (NYSE: URI) also came very close to double-digit intraday gains.

Now what: RSC is an exclusively North American business and doesn't have any interests in China, but Caterpillar's relatively big buy is renewing investor confidence in the construction industry as a whole. RSC shares have now bounced more than 62% off midsummer lows while United Rentals doubled over the same period. Investors may be betting on buyout bids of their own here.

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