Smart beta strategies and fixed income are generating significant growth in assets for exchange-traded fund providers. Put them together, though, and the whole has proved to be less than the sum of its parts.

Fixed income smart beta ETFs - those that track bond indices weighted by factors other than market capitalisation - trail far behind their equity cousins. Even in the most developed market, the US, assets in smart beta bond ETFs stood at $4.5 billion by November 2015, according to data and analytics business FactSet, just 1.4% of all the assets in fixed income ETFs. In Europe, Morningstar data suggests little more than 1% of the total strategic beta ETF market is in fixed income.