iShares Short-Term National Muni Bond ETF (SUB) is an exchange-traded fund in the Muni National Short category. It has $11.38B in assets, an expense ratio of 0.07% and a 2.52% dividend yield. The fund will invest at least 80% of its assets in the component securities of the underlying index, and the fund will invest at least 90% of its assets in fixed income securities of the types included in the underlying index that the advisor believes will help the fund track the underlying index. The underlying index includes municipal bonds, the interest of which is exempt from Federal income taxes and not subject to alternative minimum tax.