Why do banks go bust?

We've all become acutely aware in recent years just how easily a major bank can reach the point of collapse, be it Royal Bank of Scotland, Citigroup or Dexia.

Banks are responsible for our savings, mortgages and business loans. So when a big bank gets into trouble, it can hurt all of us.

So how do banks go bust? BBC business editor Robert Peston explains.

You can find out more on our special report: The global economy - making it clear