The announcement came as the judge handling the $18 billion bankruptcy case urged Detroit to resolve disputes with suburbs that rely on it for water and sewer services.
Detroit will ask the judge to let it seek votes on a debt - reduction plan filed last month by emergency manager Kevyn Orr. That plan would reduce pensions to police officers, firefighters and other city employees.
The swaps, tied to pension obligation bonds issued in 2005 and 2006, were designed to protect against rising interest rates by requiring the banks to pay the city if rates rose above a certain level.