Exchange traded fund (ETF) is a fund that trades on an exchange like a stock. Some of the features of bond ETFs in the market place are:-

• The market price of these shares will fluctuate as the collective price underlying securities.
• Due to uncertainty of conditions investors sometimes sell shares at the same time which results in crashing the market price. Market of these shares is very volatile.
• There is a complete transparency in pricing, centralized trading, and visibility to all as a result there is more connectivity between buyers and seller. Therefore, trading ETF bonds is less complicated and more efficient as compare to individual bonds.

If you wish to read more on ETFs, click on the link below for full article by Matthew Tucker: http://www.investopedia.com/partner/blackrock/articles/investing/041516/what-happens-bond-etfs-stressed-markets.asp