Updates of this series will be ceased on December 19, 2019. There is no direct replacement to this seasonally adjusted series. Interested users can construct a proxy of the series as the ratio of M1 from the H.6 release and the monetary base from the H.3 release. The discontinued series plotted on the same graph with the calculated data can be accessed for comparison here.
For more details, see the FRED Announcement.
Federal Reserve Bank of St. Louis, M1 Money Multiplier (DISCONTINUED) [MULT], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/MULT, February 22, 2020.