Jeffrey Snider, here:
That is not to say that paper dollars are issued by banks; they are not. Paper currency still takes the form of Federal Reserve Notes, but in the marginal monetary and banking system they are largely irrelevant. Dollars in the banking system, what is called liquidity, are created and dispersed by bank balance sheet accounting. These marginal liquidity units are digital representations of currency, ledger balances that shift daily, even by the minute. Bankruptcy and insolvency are not when you run out of Federal Reserve Notes in your bank vault, they come when you have to settle your accounts with the liquidity provider and there are no positive numbers on the right side of the computerized ledger (or when your ledger does not match your counterparty's, and that counterparty happens to be JP Morgan).
Given that global banks are the primary "money printers" in the dollar trade system (and the dollar swap standard), the Fed's role under interest rate targeting is to backstop the wholesale money markets where banks obtain short-term funding from each other. The implicit promise of interest rate targeting had been enough for the global dollar fraction to expand through accounting, regulatory and derivative leverage, providing the financing for the myriad bubbles of recent decades. The Fed did not create the bubbles directly, just provided the conditions for banks to do it for them.
