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 car renter Hertz Global (NYSE: HTZ) have jumped up by as much as 12% today on news that rival Avis Budget Group (Nasdaq: CAR) has dropped its competing bid to acquire Dollar Thrifty Automotive (NYSE: DTG).

So what: More than a year ago, Hertz originally proposed a $1.2 billion deal to acquire Dollar Thrifty, only to have Avis jump in on the action with a $1.5 billion offer a few months later. A bidding war broke out over the following year to the glee of Dollar Thrifty shareholders, recently sending shares to all-time highs. Avis has now decided to drop its pursuit "in light of current market conditions," leaving Hertz as the sole suitor.

Now what: With Avis out of the running, it will be interesting to see how Hertz will proceed. Presumably the company is still interested in acquiring Dollar Thrifty since during the bidding war it raised its initial $1.2 billion offer up to $2.2 billion in May. With Avis out of the picture and Dollar Thrifty no longer getting the pick of the litter, Hertz shareholders are clearly excited about the prospect of possibly getting a better deal.

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