Naugatuck, Conn.-based Ion Bank is expanding into Massachusetts by merging with The Cooperative Bank, Boston. .The merger is expected to close in the fall and will result in a $3.3 billion bank. After the deal, The Cooperative Bank will operate as the TCB Division of Ion Bank. A subsidiary of Ion Financial, the $2.7 billion Ion Bank has 20 branches in Connecticut and a dozen branches in New Jersey. The Cooperative Bank has four branches in Greater Boston, and $540 million in assets.The Cooperative Bank President and CEO John Battaglia and Directors Heather Jenkins and Clayton Samuels will be offered a position on the Ion Financial and Ion Bank boards of directors. Battaglia will join Ion Bank as president of its TCB Division. The deal was announced after Ion Bank acquired Englewood, N.J.-based NVE Bank in New Jersey in April 2025. Washington, D.C.-based Luse Gorman was legal counsel to Ion Bank, while Performance Trust Capital Partners, Chicago, financially advised Ion. Pittsburgh-based K&L Gates LLP is legal counsel to The Cooperative Bank.