Proshares UltraShort DJ-UBS Crude Oil Experiences Big Outflow
November 06, 2012 at 11:03 AM EST
Symbols mentioned in this story: SCO Exchange traded funds (ETFs) trade just like stocks, but instead of ''shares'' investors are actually buying and selling ''units''. These ''units'' can be traded back and forth just like stocks, but can also be created or destroyed to accommodate investor demand.