PITTSFIELD, Mass. — The county's largest bank is getting bigger with the addition of 20 retail bank branches in New York.

Berkshire Bank, a subsidiary of Berkshire Hills Bancorp. Inc., has entered into a purchase-and-assumption agreement for bank branches from Bank of America. The branches are located in New York markets within or contiguous to markets currently served by Berkshire.

The acquired branches have approximately $640 million in total deposits and $5 million in loans. Both banks will be working to ensure a seamless transition for customer accounts; employees will transfer over to Berkshire Bank.

This acquisition is subject to regulatory approval from the Federal Deposit Insurance Corp. and the commonwealth of Massachusetts and the satisfaction of customary closing conditions. The acquisition is expected to be completed in the first quarter of 2014.

According to Berkshire, the acquisition will increase its total branch count to 94, and its New York branches to 37. Berkshire has $5.2 billion in assets.

Berkshire CEO Michael Daly said in a statement that the "transaction meets our financial criteria and is expected to contribute to our long-term strategic and financial goals."

Jefferies LLC was financial adviser to Berkshire and Luse Gorman Pomerenk & Schick P.C. was outside legal counsel. A presentation with additional information about the deposit acquisition will be posted on Berkshire's Investor Relations website.