RiverFront Global Allocation ( RMGAX) holds a mix of stocks and ETFs. The portfolio has 8.5% of assets in Vanguard Large-Cap ETF ( VV), 6.0% in iShares S&P SmallCap 600 Index ( IJR) and 5.6% in SPDR Barclays Capital High Yield Bond ( JNK). Many funds have turned to ETFs as a way to hold gold. A popular choice is SPDR Gold Shares ( GLD), which owns bullion. As an insurance policy, First Eagle Fund of America ( FEFAX) has 3.4% of assets in the ETF. Midas Perpetual Portfolio ( MPERX), which aims to protect assets in all market conditions, typically keeps about 20% of assets in gold and 10% in silver. Along with mining stocks, the fund currently has 18.5% of assets in SPDR Gold Shares and 4.3% in iShares Silver ( SLV). A growing number of mutual funds keep nearly all their stock assets in ETFs. Stadion Managed Portfolio ( ETFFX) relies on a variety of momentum indicators to pick holdings. If technology stocks are climbing, the fund buys an ETF in that sector. With large stocks climbing last summer, the fund had 25% of assets in SPDR S&P 500, 20% in iShares S&P 100 Index ( OEF) and 20% in SPDR Dow Jones Industrial Average ( DIA). Some retirement funds rely heavily on ETFs. Managed by Lincoln Financial Group, Presidential Protected Profile 2010 ( PZAAX) is a cautious choice that emphasizes bond ETFs. The fund has 12% of assets in iShares Barclays TIPS Bond ( TIP) and 24% in Vanguard Total Bond Market ETF ( BND). Presidential Protected Profile 2050 ( PZEAX), a more aggressive choice for young people, has 25% of assets in Vanguard MSCI EAFE ETF and 5.7% in iShares Russell 2000 Index ( IWM). By focusing on ETFs, the funds can hold down fees, an important consideration at a time when many retirees are keeping a close eye on costs. This article is commentary by an independent contributor, separate from TheStreet's regular news coverage.