by Calculated Risk on 10/20/2007 02:40:00 PM

From the WSJ: SIVs Pose Risks for Money-Market Funds

Complex investments known as SIVs are roiling Wall Street and the world of high finance. But the investment vehicles also are threatening trouble in a seemingly unlikely place: money-market funds, the choice for many individual investors seeking safety.

In recent years, the short-term debt issued by such structured investment vehicles, or SIVs, had become a favorite for many money-market funds, thanks to their attractive yields, high credit ratings and added diversification.

As a result, many money-market mutual funds were holding 10% to 20% of their portfolios in debt issued by SIVs. Funds overseen by Bank of America Corp.'s Columbia Management Group, Credit Suisse Group's Credit Suisse Asset Management, and Federated Investors Inc. recently held big stakes in SIVs, including some of the most troubled names.
...
Most important for money-fund investors, fund companies would almost certainly take steps to prevent losses from reaching shareholders -- such as absorbing the losses themselves by purchasing the money-losing securities from the fund at their full price.

SIVs really aren't that complicated. They borrow short (via commercial paper less than 9 months duration so the don't have to file with the SEC) and lend long. Money market funds buy the commercial paper with deposits from their customers. Here is a good description:

... bankers hatched the idea of setting up a fund that would issue short-term commercial paper and medium-term notes to investors, then use the money to buy higher-yielding assets, typically longer-term ones. The bank would profit by collecting fees for operating the fund. The fund's assets would belong to its investors, so they would stay off the bank's balance sheet. SIVs had an advantage over conduits, a similar structure that was already gaining popularity: They didn't require banks to cover fully the fund's debts if the commercial-paper market dried up.

The funds can be off balance sheet because - at least theoretically - the investors (like the money market funds) will take the losses, not the banks. What is complicated (really opaque to the investors) is the quality of the SIVs investments.

Usually the main concern with borrowing short and lending long is interest rate risk. In this case, the problem is more credit risk with poor performing longer term investments.