Abstract: In March 2023 Silicon Valley Bank, the 16th largest bank in the United States, was forced into FDIC-administered receivership and sold to a private acquirer after it experienced a bank run of a size and speed that were unprecedented in U.S. banking history. Its failure set off runs on two other large U.S. banks, Signature and First Republic, which were also forced into receivership and sold to private acquirers. Though each bank sought liquidity from the Federal Reserve as the lender of last resort, in no case was the lender of last resort successful in averting the bank’s collapse. This article seeks to understand why. We document operational, procedural, and policy flaws in the design of the lender of last resort function and the manner in which it was deployed by banking agencies. We find that these flaws rendered the lender of last resort function ineffective in preventing contagion arising from a liquidity crisis, the very purpose for which it was intended. We then make eleven recommendations for how policymakers can improve the lender of last resort function so that it can prevent the recurrence of similar crises.