Central bank balance sheet expansion, through actions like quantitative easing, is run through commercial banks. While this increases liquid central bank reserves held on commercial bank balance sheets, demandable uninsured deposits issued to finance the reserves also increase. Subsequent shrinkage in the central bank balance sheet may entail shrinkage in bank‐held reserves without a commensurate reduction in deposit claims. Furthermore, during episodes of liquidity stress, when many claims on liquidity are called, surplus banks may hoard reserves. As a result, central bank balance sheet expansion may create less additional liquidity than typically thought, and indeed, may increase the probability and severity of episodes of liquidity stress.

The share of secured debt issued (as a fraction of total corporate debt) declined steadily in the United States over the twentieth century. This stems partly from financial development giving creditors greater confidence that high‐quality borrowers will respect their claims even if creditors do not obtain security upfront. Consequently, such borrowers prefer retaining financial flexibility by not giving security up front. Instead, security is given contingently—when a firm approaches distress. This also explains why, superimposed on the secular decline, the share of secured debt issued is countercyclical.