MB Financial Inc. is not the only Chicago bank to see its stock pop on news of its pricey sale.

Fifth Third Bancorp announced May 21 that it reached a deal to buy MB Financial for 2.76x tangible book value with a crossover earnback period of 6.8 years. The market appeared to find the $4.7 billion price tag expensive, sending MB Financial's stock up 12.9% and Fifth Third's shares down a hefty 7.9%.

"It was an excellent price for MB shareholders, and you could see why, strategically, Fifth Third had to pay what it did to get the transaction," Gene Katz, an investment banker for D.A. Davidson, said in an interview. "MB was a property that had significant scarcity value associated with it."

With a big Chicago bank off the market, the scarcity value increased for other lenders in the area too, and especially the larger names. Wintrust Financial Corp. shares jumped 3.7% on the day and First Midwest Bancorp Inc. stock increased 3.0%.

After Fifth Third's acquisition closes, Wintrust and First Midwest will be the only two Chicago-headquartered banks with more than $10 billion of assets. At the end of the first quarter, Wintrust reported $28.5 billion of assets and First Midwest reported $14.4 billion of assets.

Some investment bankers see these banks as targets, and they are looking to other large regional names as the potential acquirers — especially in light of pending regulatory changes. President Donald Trump is expected to sign legislation this week that will raise the asset threshold at which regional banks are subject to regulations for systemically important financial institutions, or SIFIs.

"As the SIFI regulations loosen up, some of the larger banks are going to want to play in that [Chicago] market," Richard Durkes, vice chairman of investment banking for Raymond James, said in an interview. "There aren't many banks left that have some size, so I think that's what we're all thinking about today."

The deal could be a boon to smaller Chicago banks, too, said D.A. Davidson's Katz. He said the Chicago market is highly fragmented, and dominated by banks with less than $1 billion in assets. Banks that small have struggled to keep up with high fixed costs associated with regulatory compliance and technology development. With MB Financial no longer in the business of acquiring community banks, companies such as Old Second Bancorp Inc. and Byline Bancorp Inc. could be well-positioned to become more active acquirers.

Katz said both banks have the currency and the experience necessary to execute deals. "I think they could be the unexpected winners in terms of being better positioned to take advantage of the void being created by the sale of what once was a fairly aggressive acquirer in the Chicago metro area," he said.