then resold their loans in bulk to Wall Street banks. The banks, in turn, bundled the loans into high-yielding residential mortgage-backed securities (RMBS) and sold them on to investors around the world, all eager for a few hundredths of a percentage point more return on their capital. Repackaged as collateralized debt obligations (CDOs), these subprime securities could be transformed from risky loans to flaky borrowers into triple-A rated investment-grade securities.