A West Virginia bank that in the past two years has entered the Western Pennsylvania market made another significant move this week that will expand its presence in Butler County.

WesBanco and ESB Financial of Ellwood City announced Wednesday that WesBanco will acquire ESB Bank for $324.4 million, or $17.65 per share.

The two county communities that might be impacted are Cranberry Township and Zelienople, where each company has an office.

Butler County native Robert Young, executive vice president and chief financial officer for WesBanco, in an interview said both Cranberry locations would likely remain open.

WesBanco's office is on Freedom Road near Route 19. ESB's office is on Rochester Road in the BelleVue Park development near the entrance to Graham Park.

However, in Zelienople the decision is more difficult and will be made later, Young said. Both companies have locations on Main Street.

ESB's other office in Butler County, on Route 68 in Connoquenessing Township, will remain open, he said.

Under the terms of the agreement and plan of merger, which has been approved by each company's board of directors, WesBanco will exchange a combination of its common stock and cash for ESB stock.

The deal is expected to close during the first half of 2015, pending approval by shareholders of both companies and regulating agencies, according to a news release.

Todd Clossin, president and CEO of WesBanco, said in an interview the Pittsburgh metropolitan area and Western Pennsylvania are key for the Wheeling, W.Va.-based company.

“It's a very stable community, and there are a lot of growth markets,” he said.

He said WesBanco is a commercial bank, which means it can offer more in-house products and services. He said ESB's footprint in Butler, Beaver, Lawrence and Allegheny counties will serve as a distribution system for those products.

He said some of ESB's executive team has opted to leave once the deal is completed, which is normal for the industry, but he added WesBanco would keep many ESB employees.

He said the overall employment picture and office footprint will mostly remain the same.

WesBanco has assets of about $6.3 billion, deposits of $5.1 billion, loans of $4 billion and shareholders' equity of $789 million. ESB had assets of about $1.9 billion, deposits of $1.3 billion, loans of $713 million and shareholders' equity of $205 million.

The completion of the agreement will create a bank with about $8.2 billion in assets and 143 locations in Pennsylvania, Ohio and West Virginia. Twenty-three of those offices are ESB's.

WesBanco's acquisition of ESB follows its 2012 acquisition of Fidelity Savings Bank, which bolstered its presence in Western Pennsylvania, including Fidelity's two Butler County offices.

According to WesBanco's online merger presentation, WesBanco moved from the 39th largest institution in the Pittsburgh area to the 13th at that time.

When the ESB acquisition is completed, WesBanco would become the No. 10 bank player in the Pittsburgh region.

According to the news release, ESB will have two seats on WesBanco's board of directors, with one for Charlotte Zuschlag, ESB's president and CEO.

In an interview, Zuschlag said a deal had been in the works for several months.

She said in June her board of directors decided to pursue a merger and hired an investment banking firm to help with the process.

She said ESB had been pursued by other institutions for a number of years, but the timing was right now because of changes in the regulatory environment.

She said ESB has historically been a real estate lender. However, more regulatory pressure and higher costs associated with compliance made it more difficult for the bank to profit in its current state.

“It was an easy decision,” Zuschlag said. “I did not want to change our business model to add more services to compete with larger banks.”

Plus, Zuschlag said, “The corporate cultures line up, which, to me, is extremely important.”