The face value of U.S. Treasury securities lent through the Term Securities Lending Facility (TSLF). This facility was established on March 11, 2008 under the authority of section 13(3) of the Federal Reserve Act. The TSLF is a weekly facility that offers Treasury securities for loan over a one-month term to primary dealers against program-eligible general collateral. The program promotes liquidity in the Treasury security and other collateral markets and thus fosters the functioning of financial markets more generally.
Board of Governors of the Federal Reserve System (US), Securities Lent to Dealers: Term Facility (DISCONTINUED) [WTERMFAC], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/WTERMFAC, December 15, 2018.