VWOB limits its scope to USD-denominated emerging market debt. As a result, investors avoid (for better or worse) any direct impact from currency volatilities. The avoidance of locally-denominated issues limits the impact of currency volatilities on portfolio returns, though FX costs will still be an issue. Note that dollar-denominated debt doesn't imply a superior credit quality: Emerging market locally-denominated issues tend to carry higher credit ratings than USD-denominated debt. The fund also skews toward the longer end of the yield curve, resulting in longer maturity and higher sensitivity to changes in interest rates.