On Monday Van Eck Associates of New York City proudly announced that its Market Vectors Emerging Markets Local Currency Bond ETF (EMLC), launched in July of 2010, had surpassed the $1 billion mark in assets under management.

Van Eck is not alone in hitting that mark. WisdomTree of New York City has attracted $1.39 billion in assets since launching its WisdomTree Emerging Markets Local Debt Fund (ELD) in August of 2010. Even the smallest of the emerging-markets local-currency bond funds – iShares Emerging Markets Local Currency Bond Fund (LEMB), which was launched more recently in October of 2011 is reporting an inflow of $155 million in the past month — for total assets under management of $364.79 million.

So why are emerging-markets local-currency bond ETFs suddenly all the rage?