Just as digital downloads have revolutionised music and book publishing, exchange-traded funds are changing the way investors do business around the world. They have grown into a market worth $1.71 trillion according to funds manager BlackRock, up from $1.48 trillion at the start of the year.

Looking back to 1990, when ETFs were first traded in Canada, management consultant McKinsey & Co said in a recent report that "no other significant segment of the U.S. asset- management industry has grown as quickly".