Total balances maintained are balances that an institution holds in a reserve account directly at a Federal Reserve Bank.
Effective February 2, 1984, reserve computation and maintenance periods have been changed from weekly to bi-weekly. Series with data prior to February 2, 1984 have different values reported from one week to the next. After February 2, 1984, the value repeats for 2 consecutive weeks.
Board of Governors of the Federal Reserve System (US), Monetary Base; Total Balances Maintained [BOGMBBMW], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/BOGMBBMW, April 21, 2018.