"A quirk of the municipal bond market that left some borrowers paying exorbitant interest rates has now suddenly reversed and pushed interest rates to zero on billions of dollars in debt," the Associated Press reports. "Investors stuck with those bonds are now realizing they are not the short-term investment they might have expected. And student-loan agencies that are having trouble borrowing more money to underwrite loans are realizing that, if buyers continue to stay away from the $300 billion 'auction-rate securities' bond market, their finances could get squeezed hard."