BlackRock’s (NYSE: BLK) iShares unit, the world’s largest issuer of exchange traded funds, added to its rapidly growing lineup of fixed income ETFs today with the launch of the iShares Short Maturity Municipal Bond ETF (BATS: MEAR).

The actively managed MEAR “seeks to maximize tax-free income through diversified exposure to short-term municipal bonds by investing in tax-exempt municipal bonds with maturities of less than five years.  Under normal circumstances the portfolio will have an effective duration of 1.2 years or less,” according to a statement from BlackRock.

Currently, about 59.6% of MEAR’s portfolio is allocated in cash and derivatives. In terms of credit quality, 27.2% of the new ETF’s holdings are rated AA with another 11.5% rated A, according to iShares data. MEAR features a weighted average coupon of 1.61% and an effective duration of 1.06 years.

Active management “allows the portfolio management and research team to capitalize on municipal opportunities along the front of the yield curve and across the investment grade credit spectrum,” according to BlackRock.

MEAR debuts at a time of robust inflows to municipal bond ETFs, which indicate some investors are not concerned about the specter of rising interest rates. Investors “have added about $1 billion to ETFs that purchase state and local bonds, the fastest annual start since the funds started in 2007,” reports Michelle Kaske for Bloomberg.

Those inflows come after municipal bonds were one of the best-performing segments of the fixed income market in 2014, but that does not diminish the chances of positive returns in 2015. Following so called “bounce back” years, of which 2014 was one, munis typically return two-thirds of that bounce in the following, according BlackRock Managing Director Peter Hayes.