In the first group - listed from most to least risk - are iShares S&P Aggressive Allocation Fund ( AOA) rated at A, iShares S&P Growth Allocation Fund ( AOR) AOR rated at A, iShares S&P Moderate Allocation Fund ( AOM)AOM rated at A-, and iShares S&P Conservative Allocation Fund ( AOK) rated at B+. Early in your work-life, when you have more time to recover from losses it can pay to be aggressive. As you progress through the various life stages, such as young worker, married couples, child rearing, empty nesters, and golden years, it will be up to you to transition through growth, moderate, and conservative phases of your retirement plan. The second group of funds - listed from those for current retirees to those for who hope to retire three decades from now - are iShares S&P Target Date Retirement Income Index Fund ( TGR) rated at B+, iShares S&P Target Date 2010 Index Fund ( TZD) rated at A-, iShares S&P Target Date 2015 Index Fund ( TZE) rated at A+, iShares S&P Target Date 2020 Index Fund ( TZG) rated at A+, iShares S&P Target Date 2025 Index Fund ( TZI) rated at A+, iShares S&P Target Date 2030 Index Fund ( TZL) rated at A+, iShares S&P Target Date 2035 Index Fund ( TZO) rated at A, and iShares S&P Target Date 2040 Index Fund ( TZV) rated at A+. These funds have the added advantage that they gradually become more conservative over time. This option removes the need to pick a specific date on which to reduce equity exposure. So, whether you scrape together $25,000, $5,000, or $500 in savings to invest in your 401k or IRA for a more secure retirement, these ETFs are worth considering for your portfolio. -- Reported by Kevin Baker in Jupiter, Fla. For additional Investment Research check out our Ratings Research Center.