Regulators in Pakistan have taken the highly unusual step of setting a floor for Karachi’s main stock market index in an attempt to stop a series of heavy share price falls triggered by political turmoil in the country.

The emergency trading limits were imposed to stem a decline that had seen the benchmark index tumble 42 per cent since April. On Wednesday, the KSE-100 fell 3 per cent to close at 9,144, its lowest level in more than two years.