Exchange traded funds (ETFs) have become more popular in recent years, particularly with online investment companies.
Many of the robo-advice propositions on the market rely on ETFs because they represent a low-cost, passive way of investing.
The rising popularity of passives was demonstrated recently when fund manager Invesco Perpetual confirmed a deal to buy ETF provider Source, with some reports suggesting it could be worth as much as $500 million.
In the fifth part of Citywire's conversation with four asset management chief executives, we talk about some of the liquidty risks posed by ETFs and potential dangers for investors.
However, this is not a one-sided discussion defending the active fund management industry. Both M&G's Anne Richards and Investec's Hendrick du Toit believe ETFs can be useful for investors.
You can see other videos in the series below