The iShares MSCI Emerging Markets ETF (NYSEArca: EEM), which tracks the MSCI EM Index, and Vanguard FTSE Emerging Markets ETF (NYSEArca: VWO), which reflects the performance of the FTSE Emerging Index, are the two largest emerging market-related ETFs on the market. VWO, though, excludes South Korea since FTSE categorizes the country as developed. VWO has a 0.15% expense ratio and EEM has a 0.67% expense ratio.

Lastly, for commodities exposure, the GreenHaven Continuous Commodity Index Fund (NYSEArca: GCC) follows an equal-weight methodology for its 17 commodity positions. In addition, the PowerShares DB Commodity Index Tracking Fund (NYSEArca: DBC), the largest commodity-related ETF and tracks a broad basket of the 14 most heavily traded commodities, uses an optimum yield methodology that tries to limit the negative effects of contango. GCC and DBC have a 0.85% expense ratio.

“Note that these portfolios aren’t designed to shoot out the lights over short time frames,” Benz said. “Rather, the goal is to depict sensible asset-allocation mixes for investors at varying life stages.”

Nevertheless, one should not completely set-and-forget these types of portfolios. Over time, the portfolio positions can shift, so investors should not forget to annually, if not regularly, rebalance positions. [Don’t Forget to Rebalance Your ETF Portfolio]

For more information on investing toward retirement, visit our retirement category.

Max Chen contributed to this article.