D uring weak markets, many investors become squeamish. Investment firm executive Lewis Sisich, however, says the volatility can be reduced by using types of assets that don't move in lockstep with stocks and domestic bonds. Sisich favors putting these investments into his clients' diversified portfolios to help them ride out storms. Two funds that he likes now...

Prudent Global Income (PSAFX). This world bond fund, which can benefit when the dollar is declining in value against foreign currencies, invests 50% of its portfolio in sovereign debt from other countries. It was recently generating a yield of more than 5%. Performance: 7.9% annualized returns for the five years through July 8.

PowerShares DB Agriculture (DBA). This exchange-traded fund (ETF), which is the nation's most heavily traded agricultural ETF, invests in four commodities: soybeans, corn, sugar and wheat. This fund can provide a good way to diversify a portfolio, although after its huge run-up, new investors should tread cautiously. Performance: 51% for the 12 months through July 7. Recent share price: $39.66.