Exchange-traded funds came into regulatory view in May last year with the US “flash crash”, when the Dow Jones Industrial Average plummeted nearly 600 points in five minutes, taking the index down by 1,000 points before a rally recouped much of the loss.

An investigation by the Securities and Exchange Commission cited ETFs as a significant cause of the crash. Earlier this year, 10 newly listed ETFs - not covered by the circuit-breakers that halt trading if the price moves 10% or more during a rolling five-minute period - suffered a mini flash crash, forcing stock market operator Nasdaq OMX to cancel trades.