Millions of U.S. mortgages have been shuttled around the global financial system – sold and resold by firms – without the documents that traditionally prove who legally owns the loans. Now, as many of these loans have fallen into default and banks have sought to seize homes, judges around the country have increasingly ruled that lenders had no right to foreclose, because they lacked clear title. These fundamental concerns over ownership extend beyond those that surfaced over the past two weeks amid reports of fraudulent loan documents and corporate “robo-signers.” The court decisions, should they continue to spread, could call into doubt the ownership of mortgages throughout the country, raising urgent challenges for both the real estate market and the wider financial system.