Pricing turmoil in the currency markets has prompted scores of private investors to look to trade US dollars, yen and sterling – or buy into currency funds – in an attempt to make money on the swings in spreads.

The foreign exchange broker Caxton FX has seen a 400 per cent increase in trading activity in the past month – with traders putting up £150,000 to £200,000 for each transaction on average, according to Rupert Lee-Browne, the firm’s chief executive.