An SEC filing tells us, "In March 2024, the Board of Trustees of Vanguard Municipal Cash Management Fund (MCMT) approved (1) the reclassification of MCMT from an institutional tax-exempt money market fund to a short-term municipal bond fund, and (2) MCMT's name change to Vanguard Municipal Low Duration Fund.... Under the 'Cash Management' heading, the following replaces the first sentence: The Fund's (for Vanguard Variable Insurance Funds, 'The Portfolio's') daily cash balance may be invested in Vanguard Market Liquidity Fund, a low-cost money market fund, and/or Vanguard Municipal Low Duration Fund, a short-term municipal bond fund (each, a CMT Fund)."