Another short-term US muni market starts to freeze

By Joan Gralla

NEW YORK, Feb 22 (Reuters) - Some of the same hazards that caused the U.S. auction rate market to collapse are now spilling over into a supposedly safer cousin.

Known as variable rate demand notes, this short-term debt vehicle was designed to protect investors from the risk that their cash would be frozen if no one else wanted it.

Variable rate demand notes are backed by letters of credit, which improve the debt's rating, or standby purchase agreements, which oblige agents to repurchase the paper.

But now some repurchase safeguards are fraying -- partly because the notes are tied to bond insurers whose faulty subprime mortgage plays could cost them their "AAA" ratings.

"Variable rate notes are considered the highest standard in liquidity, and when you start to see these things stop functioning normally, you have to know something's wrong," said Chris Ihlefeld, a co-portfolio manager of muni debt at Thornburg Investment Management in Santa Fe, New Mexico.

U.S. states, cities and agencies sold around $60 billion of variable rate demand notes in 2006, according to Thomson Financial. These notes can vary widely, depending upon how their documents are written.

In some cases, only one credit agency has to cut an insurer's "AAA" rating to free the dealer from having to buy the debt back. In other instances, the dealer must repurchase the debt unless all three credit agencies cut the insurer.

Some dealers are resorting to highly unusual methods to avoid having to buy back variable rate demand notes.