Abstract: Money market funds (MMFs) are popular around the world, with over $9 trillion in assetsunder management globally. From their origins in the 1970s, MMFs have operated in a niche betweenthe capital markets and the banking system, as investment funds that offer private money‐like assetswith features similar to those of bank deposits. Hence, they are vulnerable to runs that arise fromliquidity transformation and from sudden changes in investor perceptions of the funds’ ability to serveas money‐like assets. Since 2000, MMF runs have occurred in many countries and under manyregulatory regimes. The global pattern of runs and crises shows that MMF vulnerabilities are not uniqueto a particular set of governingarrangements, and that mitigating these vulnerabilities requiresfundamental reforms that either place MMFs more clearly within the investment‐fund sector orestablish protections for MMFs similar to those for deposits.