The WSJ had an article entitled Auction-Rates a Legal Tangle recently. There have been recent liquidity problems in the $330B or so market for this special type of security, and this might be leading to claims against firms in this market.
The securities were unusual in the sense that they were a means of raising money long term (actually a form of long-term bond) wherein the interest rate was reset periodically (weekly or monthly) using auctions (so the bonds acted more like short-term securities in that the interest rate could be reset or the security could be sold in the auction).
The article pointed out that the defense of claims made be made more difficult because Wall Street firms themselves often bid in the "auctions" when there were no other bidders.
