Boston-based Eastern Bank Corp. has completed its acquisition of MASSBANK Corp., parent company of Reading-based MASSBANK.

The acquisition created a $7 billion institution serving more than 400,000 consumers and businesses across eastern Massachusetts, Eastern Bank said.

The cash transaction, valued at approximately $170 million, or $40 per share, has received all necessary state and federal regulatory approvals, as well as the approval of MASSBANK’s shareholders.

The merger increases Eastern’s presence in Middlesex County, where all of MASSBANK’s 15 offices are located.