By definition, nonborrowed reserves are equal to total reserves minus borrowed reserves. Borrowed reserves are equal to the sum of credit extended through the Federal Reserve's regular discount window programs and credit extended through certain Federal Reserve liquidity facilities. Total borrowings from the Federal Reserve are presented in table 1a of the release. Over much of 2008, in order to maintain a level of total reserves consistent with the Federal Open Market Committee's objective for the federal funds rate, increases in borrowed reserves were offset through a nearly commensurate decrease in nonborrowed reserves, which was accomplished through a reduction in the Federal Reserve's holdings of securities and other assets. The negative level of nonborrowed reserves was an arithmetic result of the fact that borrowings from the Federal Reserve liquidity facilities were larger than total reserves.
This series has been discontinued. As of July 11, 2013 data in the new H.3 statistical release are no longer adjusted for regulatory changes in reserve requirements and are no longer seasonally adjusted. You can access the not seasonally adjusted series at https://fred.stlouisfed.org/series/NONBORRES.
Board of Governors of the Federal Reserve System (US), Non-Borrowed Reserves of Depository Institutions (DISCONTINUED) [BOGNONBR], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/BOGNONBR, June 19, 2021.