Magazine. This one is no exception. For that I thank Hugo Lindgren, Adam Moss, and Gerry Marzorati; also, thanks to Vera Titunik and Paul Tough for inviting the Bagel Man into the Magazines pages. I am most grateful to Steven Levitt, who is so clever and wise and even kind as to make me wish-well, almost-that I had become an economist myself. Now I know why half the profession dreams of having an adjoining office to Levitt. And finally, as always, thanks and love to Ellen, Solomon, and Anya. See you at dinnertime. -S. J. D. he money market is traditionally defined as the market for financial assets that have original maturities of one year or less. In essence, it is the market for short-term debt instruments. Financial assets traded in this market include such instruments as U.S. Treasury bills, commercial paper, some medium-term notes, bankers acceptances, federal agency discount paper, most certificates of deposit, repurchase agreements, floating-rate agreements, and federal funds. The scope of the money market has expanded in recent years to include securitized products such mortgage-backed and asset-backed securities with short average lives. These securities, along with the derivative contracts associated with them, are the subject of this book. The workings of the money market are largely invisible to the aver- age retail investor. The reason is that the money market is the province of relatively large financial institutions and corporations. Namely, large borrowers (e.g., U.S. Treasury, agencies, money center banks, etc.) seek- ing short-term funding as well as large institutional investors with excess cash willing to supply funds short-term. Typically, the only contact retail investors have with the money market is through money market mutual funds, known as unit trusts in the United Kingdom and Europe. Money market mutual funds are mutual funds that invest only in money market instruments. There are three types of money market funds: (1) general money market funds, which invest in wide variety of short-term debt products; (2) U.S. government short-term funds, which invest only in U.S. Treasury bills or U.S. government agencies; and (3) short-term munic- ipal funds. Money market mutual funds are a popular investment vehicle for retail investors seeking a safe place to park excess cash. In Europe, unit trusts are well-established investment vehicles for retail savers; a number oftheseinvestinshort-termassetsandthusaretermedmoneymarketunit