Brown Deer-based Bank Mutual plans to open a new, 4,000-square-foot branch in the 500,000-square-foot Fountains of Franklin retail development, which is being developed by Equitable Development LLC and Devo Properties LLC at South 51st Street and Rawson Avenue in Franklin. The bank will be built on an outlot near a 61,520-square-foot Sendik’s grocery store. A groundbreaking ceremony was held last week for the grocery store, which will be built by Oconomowoc-based MSI General Corp. Bank Mutual has $3.5 billion in assets and 77 locations in Wisconsin and one in Minnesota.