If the price of IEF is moving higher at a faster rate than MUB (or MUB is falling and IEF is rising), then municipal bonds are underperforming the market.

FORBES: Connect

And if the prices of your old debt are falling then the yields on that debt are rising (bond prices and yields move inversely) and thus you have to pay more for new borrowings: for the new debt is priced compared to the old.

FORBES: Eurobond Contagion: Or What's Really Wrong With the Eurozone

If the price of MUB is moving higher at a faster rate than IEF (or MUB is rising and IEF is falling), then municipal bonds are outperforming the market.

FORBES: Connect

Dune after dune, rising and falling beneath his feet, then finally falling, falling, falling all the way to a gray-green-blue vastness, riffled, glinting, and crossed by the cloud shadows as far as the eye could see.

NEWYORKER: Ziggurat

The market had basically held true to its news-driven moniker by falling on bad news relating to the risk of a nuclear catastrophe and then rising when those worries abated in the afternoon.

FORBES: New Wall Street Term for 2011: De-Risking