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: RSC Holdings (NYSE: RRR) shares climbed as much as 12% in intraday trading Friday after Oppenheimer upgraded the equipment rental specialist to outperform from perform.

So what: Citing a rental services market that seems poised for a rebound this year, Oppenheimer also offered a $15 price target on RSC Holdings' shares, representing about 40% worth of upside to yesterday's close. Not surprisingly, equipment rental rivals United Rentals (NYSE: URI) and H&E Equipment (Nasdaq: HEES) are also up handsomely on the forecast.

Now what: I'd be cautious about buying into RSC Holdings. While betting on a sector turnaround might pay off in the short term, the company's debt-to-capital ratio of 1.2 is just too dangerous for most long-term portfolios. And when you consider that these shares have now gained more than 50% over the past three months alone, the decision to stay away is that much easier.

Interested in more info on RSC Holdings? Add it to your watchlist.

Fool contributor Brian Pacampara doesn't own a position in any of the companies mentioned. Try any of our Foolish newsletter services free for 30 days.

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