Bank deposits, which are part of reserves, also dropped with customers seeking higher-yielding alternatives for their cash.
Lower reserves constrain banks' balance sheets, hampering their ability to lend to finance corporate growth and expansions, analysts said.
As of March 8, bank reserves during the week averaged $2.999 trillion, Fed data show, falling around $1.3 trillion from a peak of $4.3 trillion in December 2021.
Volumes on reverse repos have hit north of $2 trillion since June last year, even as bank reserves have dwindled.
And cash assetsDeposit outflows, reverse repos, and bank reserves are all inter-related.