Bangor Savings Bank announced Monday that it has signed an agreement to acquire Biddeford-based Pepperell Bank & Trust, thereby expanding its business in York County.

Over the past several months, Bangor Savings Bank has grown rapidly in York and Cumberland counties. It already owned two branches, built three more this winter, and will acquire five Pepperell Bank & Trust branches, bringing the total to 10 in southern Maine.

It already had one branch in the York County town of Cornish.

Bangor Savings said the acquisition strengthens its standing as Maine’s largest independent bank. Pepperell Bank & Trust will operate under the Bangor Savings Bank name upon completion of the transaction, which is expected to happen at the end of the summer.

The financial terms of the sale were not disclosed.

“We are pleased to bring more York County customers our great business banking services, our innovative offerings, like free ATMs worldwide, and our exceptional customer service built on our brand promise, ‘You Matter More.’ We also look forward to bringing our focus on community and philanthropy to the region,” said Bangor Savings Bank President and CEO Jim Conlon.

Said Pepperell Bank & Trust Chairman and CEO George Giovanis: “We view this deal as a very strong opportunity to gain value for our shareholders while at the same time pairing our franchise with a great, independent, Maine-based bank, Bangor Savings, which has the capacity to provide our customers with all of the products and services they need in today’s more complex banking environment.”

Giovanis said the decision to sell the bank had mainly to do with its size.

“We’re small and today with the cost of regulatory compliance, technological innovations, it’s cost-prohibitive for a small bank. We can’t offer the array of products and services that a bigger bank can,” Giovanis said.

Giovanis said he considered selling to other banks, but decided Bangor Savings was the best fit for his customers.

“We looked at other banks, considered a number of factors, but at the end of the day it looked like Bangor had the most to offer our customers and their management team was the most in sync with ours in terms of valuing the primary importance of customer service, providing competitive pricing, and technologically innovative features,” Giovanis said.

Giovanis said the acquisition should not affect Pepperell Bank & Trust customer accounts, most of which are held by residents in southern Maine.

Conlon characterized the transaction as consistent with Bangor Savings Bank’s strategic plan for growth.

“Our core market has been in eastern Maine for more than 150 years, but over the past 30 years we have gradually expanded to all regions of the state, including inland York County in Cornish,” Conlon said. “We are committed to being an independent Maine bank, and that means seeking opportunities to grow where Maine is growing most by serving more customers in southern Maine.”

Bangor Savings Bank does not plan to expand out of state, according to Senior Vice President Yellow Light Breen.

Conlon said Bangor Savings anticipates making significant investments to upgrade Pepperell branch facilities.

For legal reasons, the transaction took place between the banks’ parent companies, Bangor Bankcorp and Pepperell Bancshares Financial Group Inc.

The boards of directors of both banks have approved the deal, which now awaits approval from regulatory agencies and Pepperell Bancshares Financial Group shareholders.

Bangor Savings Bank was founded in 1852 in Bangor and operates 46 locations throughout Maine. Following the acquisition, it will have a combined estimated $2.2 billion in assets and $1.6 billion in deposits.

Pepperell Bank & Trust was founded in 1907 and operates the five branches in York County. It has approximately $100 million in assets, with $60 million in loans outstanding and $87.5 million in deposits.