“Since 2007, when the PowerShares Insured Municipal Bond Portfolios first listed, the US market for insured municipal bond securities has shrunk by over 40 percent, making the available supply of insured-municipal securities more limited. The new indexes underlying the PowerShares’ Municipal Bond ETFs include both insured and uninsured municipal bonds,” according to PowerShares.

Table Courtesy: PowerShares

ETF Trends editorial team contributed to this post.