“They’re still very suitable investments,” Agather said. “As you say, the majority of assets and flows, even, are still in some of the early products that were created. Lots of liquidity and, again, low cost.”

For example, some of the most popular ETFs include FTSE index-based options like the Vanguard FTSE Emerging Markets ETF (NYSEArca: VWO), iShares Russell 1000 Value ETF (NYSEArca: IWD) and iShares Russell 2000 ETF (NYSEArca: IWM).

VWO, which has $70.4 billion in assets under management and a cheap 0.14% expense ratio, tries to reflect the performance of the FTSE Emerging Markets All Cap China A Inclusion Index. The underlying portfolio includes access to developing market stocks, along with exposure to China’s domestic A-share market, which the benchmark MSCI Emerging Markets Index has yet to include.

IWD, which has $36.3 billion in assets and a 0.20% expense ratio, focuses on the Russell 1000 Value Index. The underlying index provides exposure to the large-cap segment of the U.S. markets, but only those thought to be undervalued by the market relative to comparable companies.

Lastly, IWM, which has $35.7 billion in assets and a 0.20% expense ratio, tries to reflect the performance of the widely observed Russell 2000 Index. The benchmark is a popular gauge of the small-cap segment of the U.S. markets.