The article discusses how the Federal Reserve's actions during the financial crisis affected interbank trading and excess reserves. It shows how financial shocks can impact the real economy and how injecting liquidity can help stabilize it. The study finds that the federal funds market is not crucial for normal supply and demand shocks, but it does matter for uncertainty shocks related to liquidity risk. Overall, central bank interventions can mitigate the effects of financial shocks on the economy, even though they may lead to an increase in excess reserves and a decrease in federal funds trading.