The Federal Reserve published a "History" piece on "Money Market Mutual Funds," which gives a nice basics and brief overview of the asset class. They write, "Money market mutual funds (​MMMFs) arose in the 1970s. At the time, market interest rates were higher than the rates that commercial banks were permitted to pay on their deposits by federal banking regulation, spurring the growth of investment alternatives outside of banks including MMMFS. Since MMMFS are not banks, they developed largely outside of the sphere of Federal Reserve operations or regulations until the advent of severe financial crises in 2008 and 2020, when the Fed made emergency loans to support MMMFs and the broader economy. In addition, since 2013 the Fed has interacted with MMMFs regularly through open market operations in the context of implementing monetary policy." The Fed explains, "Money market funds began largely as a workaround to regulations that limited the interest rates depository institutions were allowed to pay depositors. These limits, known as Regulation Q, were required by federal law beginning in 1933 and were implemented by the Federal Reserve and other financial regulators. As interest rates rose in the 1970s, Regulation Q gave depositors an incentive to find short-​term investments outside of the banking system, such as Treasury bills, commercial paper, and repurchase agreements. MMMFs offered consumers the ability to invest in those instruments with some additional conveniences, including the ability to withdraw funds at any time, diversify across instruments, choose any specific investment size, and economize on administrative expenses." They comment, "These basic forces led to the establishment of the first MMMF in 1972. The number of funds grew to 36 in 1975, 90 in 1980, and 649 in …