INTRODUCTION: Money market funds ("MMFs") were first developed in the 1970s, and since that time, they have become increasingly popular as an alternative to deposit accounts. Since the financial crisis of September 2008, there has been much discussion about the systemic risks posed by alternatives to commercial banking products. One of the key themes of this discussion is whether the systemic importance of these alternative banking products justifies the imposition of heightened regulation and supervision. This article takes the view, after a comparison of deposit accounts and MMFs, that MMFs are systemically important. It then goes on to consider, through the lens of systemic risk analysis, the reforms to MMF regulation that have been proposed since September 2008.