The lowest yields in 40 years and concern over their tax-exempt status sent municipal bonds into their worst monthly decline since 2010, according to InvestmentNews (“Munis take worst pounding since Meredith Whitney”). As of December 21, municipals were on track to lose 1.9 per cent of their market value for the month. Thanks to the price decline, yields on AAA rated municipal bonds are in the 1.8% range, the highest since August, according to Bloomberg data.