BOSTON (AP) – Eastern Bank, New England’s largest independent, mutually owned bank has signed an agreement to acquire MASSBANK Corp. for about $170 million in cash.The deal announced Tuesday marks Eastern Bank Corp.’s third acquisition in four years as it expands its operations in eastern Massachusetts.The deal is expected to close in the second half of this year, subject to approval by state and federal regulators as well as shareholders of Reading-based MASSBANK.The boards of directors of both companies have already approved the merger that will create a $7.6 billion bank with more than 400,000 customers.Eastern’s chairman and CEO Richard Holbrook will lead the merged bank, while the head of MASSBANK will become the vice chairman.”Middlesex County is an important market for Eastern and this agreement improves our presence there, while enabling us to better serve customers at both banks,” said Holbrook.MASSBANK operates 15 branches in Reading, Chelmsford, Dracut, Everett, Lowell, Medford, Melrose, Stoneham, Tewksbury, Westford and Wilmington. Chartered as a savings bank, MASSBANK’s acquisition by Eastern – a full-service commercial bank – will enable its locations to better serve the small business community with lending and cash management services.”By combining our resources with Eastern, we can offer both the advantages of a larger bank – including up to date technology, access to a larger network of ATMs and branches and greater product diversity – while simultaneously ensuring that a locally operated bank will serve our communities for many years to come,” Brandi said. Brandi is expected to become a vice chairman of Eastern Bank Corporation following the merger.