MBSs and CDOs give their buyers the right to received the payments on the underlying mortgage, and banks bought them because they believed that house prices would continue to rise, and households would continue to make their mortgage payments, But when many subprime related securities fell dramatically. Many banks in the USA, Britain and elsewhere lost billions of dollars on their MBSs; some went bankrupt, and others had to be rescued by governments. It is estimated that banks around the would will eventually have to write off $1.5 trillion of worthless subprime MBSs [now often referred to as "toxic debt"]. These losses destroyed much of the capital of the world banking system, leading to a credit crisis or a " credit crunch": a massive reduction in the amount of credit available for banks to other banks, businesses and households.