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 regional bank Tower Bancorp (Nasdaq: TOBC) surged 30% on Tuesday after agreeing to be acquired by Susquehanna Bancshares (Nasdaq: SUSQ) for $343 million in cash and stock.

So what: The deal, in which Tower shareholders can opt for either 3.47 shares of Susquehanna or $28 in cash for each share owned, represents a 41% premium to Tower's Friday closing price. Susquehanna is making the move to strengthen its presence in Philadelphia, but judging from the stock's 10% plunge today, Mr. Market doesn't seem pleased with the price that it's paying to do it.

Now what: While Tower's upside is now limited, Susquehanna should have plenty of room to run. Once you include its pending acquisition of smaller peer Abington Bancorp, Susquehanna stands to become Philadelphia's largest community bank with total assets of about $17.8 billion. With Susquehanna shares now down about 25% year-to-date, it might even be a good time to bet on significant cost savings, increased efficiencies, and a stronger competitive foothold going forward.

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