“A wave of selling caused many exchange traded funds to tumble below the value of their underlying assets as a bond market sell-off caused stress in the $2 trillion ETF industry. Emerging-markets ETFs were among the worst affected, as investors took fright that the end of Federal Reserve monetary easing would lead to outflows from developing countries. The selling also caused disruptions in the plumbing behind several ETFs. Citigroup stopped accepting orders to redeem underlying assets from ETF issuers, after one trading desk reached its allocated risk limits. State Street said it would stop accepting cash redemption orders for municipal bond products from dealers.”
