As the dust has settled on the financial crisis, there has been much debate about what changes to the system should occur to avoid a repetition of the past two years. A recurring theme has been the role played by hedge funds and in particular whether the practice of short selling bank shares was a major contributor to last autumn's instability.

At the height of the sell-off, the UK's Financial Services Authority imposed a ban on shorting financial stocks and since this was lifted in January the regulator has required disclosure of short positions in a list of vulnerable companies. In some other markets bans remain in force.