Of course, QE is not necessary. A recent case is that during the Silicon Valley banking crisis in March 2023, many small and medium-sized banks were in a liquidity crisis. The Federal Reserve pulled out a BTFP bank term financing tool (commercial banks use eligible assets as collateral, and the Federal Reserve provides loans to these eligible banks for up to one year to help them cope with the liquidity crisis). This does not count as QE, which is a type of balance sheet expansion (during this period, the Federal Reserve's balance sheet was expanding). Tools like these to release liquidity are all part of expanding the balance sheet