A low-cost option from Vanguard for emerging market stocks is the top-selling ETF this year with more than $6 billion of inflows despite investors pulling some cash in May’s risk-off pullback.

Vanguard MSCI Emerging Markets (NYSEArca: VWO) has attracted $6.4 billion year to date although the ETF saw redemptions of $622 million last month, according to ETF Industry Association data.

The fund has seen much higher inflows in 2012 than competitor iShares MSCI Emerging Markets (NYSEArca: EEM), which tracks the same index.

VWO has lower fees with an expense ratio of 0.20%, versus 0.67% for EEM. [Investors Pull Over $2 Billion from Largest Emerging Market ETFs]