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 Florida-based BankAtlantic Bancorp (NYSE: BBX) were off as much as 15% in intraday trading on heavy volume.

So what: Just last week, we were watching BankAtlantic shares head for the rafters as traders speculated on the potential for the bank to be bought out by PNC Financial (NYSE: PNC). It's been all rumors thus far, with word on the street suggesting that PNC's sights are trained on both Regions Financial (NYSE: RF) and BankAtlantic. BankAtlantic's CEO lent some credence to the buyout rumors by saying that though the bank has said it wants to remain independent, it's also staying "flexible and open to opportunities as they may be presented." There was even more banking-buyout excitement sparked on Friday as Canada's Bank of Montreal (NYSE: BMO) announced the buyout of Marshall & Ilsley (NYSE: MI). But it would appear that today's traders are questioning the veracity of the rumors and are backing away from BankAtlantic a bit.

Now what: What's an investor to do? To the extent that it's possible, they're probably best served tuning out the rumors and focusing on what they think BankAtlantic is really worth. Sure, a buyout could bring a quick pop to the stock, but rumored acquisitions often never come to fruition, so investors watching the stock today should make sure they'd be pretty comfortable owning the underlying bank even if a deal never pans out.

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