FYI: (Click On Article Title At Top Of Google Search)
Bond exchange-traded funds are the late bloomers of the otherwise hot ETF market. The main holdup? Liquidity.
Investors, regulators, and even some ETF providers have focused their concern on the more thinly traded areas of the bond market, such as high-yield bonds and bank loans. Specifically, what happens when there’s a sharp selloff, causing prices of rapidly traded ETFs to fall—and would a selloff in certain bond markets prove perilous to the ETFs that own them.
Regards,
Ted
https://www.google.com/#q=Quelling+Liquidity+Concerns+of+Bond+ETFs+Barron's