Do credit rating agencies help or hinder financial stability?
For decades, the credit rating agencies were rarely heard of outside of financial markets, but now news of their downgrades regularly features in the headlines.
Downgrades of sovereign ratings around Europe have provoked angry reactions and there is an ongoing police investigation in Italy - and this week the Commons Treasury Select Committee begins an investigation into their activity.
However, Alistair Darling has told the BBC he found the threat of a UK downgrade "helpful" when he was Chancellor of the Exchequer.
So do credit rating agencies help or hinder financial stability? Chief economics correspondent Hugh Pym investigates for File on 4.
28 Feb 2012