This listing includes some, not all, of the many municipal bond ETFs that have proliferated over the past few years as issuers have discovered a reasonable way to price related indexes. After all, since bonds are a "dealer market" vs a listed securities market where valuations are transparent, pricing bonds has always been in the eye of the various bidders. A reasonable summary of this difficulty was published by Dan Seymour of the Bond Buyer in January 2011: "The muni market includes more than 60,000 issuers and at least 1.2 million CUSIP numbers. Munis are considered less liquid than Treasury or corporate bonds. Some muni bonds never trade, and most trade infrequently. Indexes designed to reflect values in the municipal bond market rely on pricing services, such as Interactive Data, to evaluate bonds that aren't trading.Investors don't necessarily always believe these pricing services. It might be that a bond that would otherwise be trading at a lower price is quoted by a pricing service at a higher price simply because nobody is trading it, so there's no discovery of the lower price.That explains why municipal yield-curve scales such as Municipal Market Data and Municipal Market Advisors can often disagree on where yield levels are -- they are often extrapolating based on general conditions, rather than visible trades."Due to some late 2010 panic among investors ETFs disconnected from their indexes as selling overwhelmed index structure creating large discounts to NAV for investors. This is why MUNI ETF returns were high during 2011 as the rebound occurred early in the year and no doubt exaggerated returns. And no yields are low but not necessarily lower than taxable yields for the same maturity. I remember complaining to my boss in 1976 when yields suddenly dropped to 5% briefly for high grade general obligation bonds. He calmly said: "They'll buy 'em when they're 3% because they hate taxes always." He was right.As a former bond dealer myself with a Municipal Principal Series 53 license, I can attest on these difficulties. You may think these problems are isolated and they can be but remember the difficulty encountered by muni-bond funds one year ago when most funds were not tracking the indexes well at all. This was occasioned by investor flight given worries over municipal budgetary and fiscal soundness issues. (These problems are well-outlined in the linked article above.) But these issues can be geographic in nature as well. In 1975 the U.S. northeast was plagued by the contagion from NY City's financial crisis. Suddenly Massachusetts, Pennsylvania and other municipalities in the region had to pay large premiums given their proximity to New York. California had its problems with tax reform later and Washington Public Power went bankrupt. In 1929 nearly 70% of all municipal bonds with investment grades went bankrupt so don't be too sanguine about conditions. The latest rage in muni-land which has always had the reputation as a gimmicky market is Build America Bonds (BABS). Investors should know these bonds are federally taxable but exempt from state and local taxes for investors from that jurisdiction. Institutions such as casualty insurance companies have been feasting on these issues and this is expected to continue. We rank the top 10 ETF by our proprietary stars system as outlined below. However, given that we're sorting these by both short and intermediate issues we have split the rankings as we move from one classification to another so rankings aren't necessarily in order. Strong established linked index Excellent consistent performance and index tracking Low fee structure Strong portfolio suitability Excellent liquidity Established linked index even if "enhanced" Good performance or more volatile if "enhanced" index Average to higher fee structure Good portfolio suitability or more active management if "enhanced" index Decent liquidity Enhanced or seasoned index Less consistent performance and more volatile Fees higher than average Portfolio suitability would need more active trading Average to below average liquidity Index is new Issue is new and needs seasoning Fees are high Portfolio suitability also needs seasoning Liquidity below averageWe feature a technical view of conditions from monthly chart views. Simplistically, we recommend longer-term investors stay on the right side of the 12 month simple moving average. When prices are above the moving average, stay long, and when below remain in cash or short. Some more interested in a fundamental approach may not care so much about technical issues preferring instead to buy when prices are perceived as low and sell for other reasons when high; but, this is not our approach. Premium members to the ETF Digestreceive added signals when markets become extended such as DeMark triggers to exit overbought/oversold conditions.