Photo courtesy of Ion Bank

Ion Bank has formally filed with Massachusetts bank regulators to merge with a Boston-based bank, and is seeking public comment on the deal.

A notice was posted last week by the Massachusetts Division of Banks stating the public comment period would run through Sept. 4.

If approved, the deal between Ion Bank and The Cooperative Bank would leave Ion as the surviving institution.

The two announced in June that their depositors had voted to back the idea.

Ion would end the deal with $3.3 billion in assets and four branches in Boston’s outlying neighborhoods. That would give Ion a foothold in two of the Northeast’s biggest metro areas, following its acquisition of NVE Bank in New Jersey in 2025, in addition to its 20 branches in central Connecticut.

The deal is expected to close this fall if approved.

“We are thrilled to add TCB as a division of Ion Bank,” Rotatori said in a statement in June. “This merger reflects Ion Bank’s core mission as a mutual institution to deepen its commitment to local communities, expand access to meaningful financial services, and partner with likeminded organizations that share its values of trust, service and long-term community investment.”