From Bespoke Investment Group:
Couple the increased likelihood of an extension of the Bush tax cuts with a new Congress that has at the least put on a front of opposing further bailouts, and you get the kind of municipal bond performance we've seen in recent days.
After drifting lower from late August to early November, the National Municipal Bond ETF (MUB) has tanked this week. The California Municipal Bond ETF (CMF) has tanked as well. So far the investment world hasn't paid much attention to this big move lower in the muni-bond market, but it's likely to get coverage soon if the declines continue.