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 equipment rental company RSC Holdings (NYSE: RRR) soared a staggering 55% today after rival United Rentals (NYSE: URI) agreed to acquire it for about $1.9 billion.

So what: The cash-and-stock deal values RSC at $18 per share and represents a whopping 58% premium to its Thursday closing price. United Rentals is making the move to add "less volatile" revenue from industrial customers, and judging from its own 4% stock jump, investors seem quite satisfied with the strategy, as well as the price being paid.   

Now what: While RSC looks all popped out, United Rentals might be a long-term opportunity worth looking into. The transaction -- which should close in the first half of 2012 -- is expected to be accretive to United Rentals in the first full year and bring in more than $200 million of annual cost savings. "This transaction marks a transformative moment in our company's history," United Rentals CEO Michael Kneeland said. "We have a tremendous opportunity to become the supplier of choice for customers throughout North America."

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