The amount of securities held by Federal Reserve Banks. This quantity is the cumulative result of permanent open market operations: outright purchases or sales of securities, conducted by the Federal Reserve. Section 14 of the Federal Reserve Act defines the securities that the Federal Reserve is authorized to buy and sell.
Board of Governors of the Federal Reserve System (US), Assets: Securities Held Outright: Securities Held Outright: Week Average [WSECOUT], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/WSECOUT, May 20, 2022.
Feb 1984 - Dec 1990: Annual Statistical Digest, various issues, Table 2.
Jan 1991 to date: Federal Reserve Board, H.4.1.
Reserve balances with Federal Reserve Banks are the difference between "total factors supplying reserve funds" and "total factors, other than reserve balances, absorbing reserve funds." This item includes balances at the Federal Reserve of all depository institutions that are used to satisfy reserve requirements and balances held in excess of balance requirements. It excludes reserves held in the form of cash in bank vaults, and excludes service-related deposits
Board of Governors of the Federal Reserve System (US), Liabilities and Capital: Other Factors Draining Reserve Balances: Reserve Balances with Federal Reserve Banks: Week Average [WRESBAL], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/WRESBAL, May 20, 2022.
Total factors supplying reserve funds are the sum of "Reserve Bank credit," "gold stock," the "special drawing right certificate account," and "Treasury currency outstanding.
Board of Governors of the Federal Reserve System (US), Assets: Other Factors Supplying Reserve Balances: Total Factors Supplying Reserve Funds: Week Average [WTFSRFA], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/WTFSRFA, May 20, 2022.