Central banks use an interest rate corridor — a floor set by the deposit facility and a ceiling set by the lending facility around a central policy rate — to anchor short-term money market rates and manage interbank liquidity. The corridor defines the transaction costs for banks that are short or long of reserves, shaping their incentives to borrow or lend in the overnight market and thereby influencing the distribution and volatility of liquidity across the banking system. Research by Michael Woodford Columbia University explains how operational procedures and standing facilities determine the control a central bank exerts over market rates, while Claudio Borio Bank for International Settlements discusses the broader implications of operating frameworks for monetary transmission.
Mechanism and transmission
When the corridor is narrow, the interbank rate tends to remain close to the policy rate because banks can cheaply adjust positions via standing facilities. Narrow corridors reduce day-to-day rate volatility and make the central bank’s policy signal more precise. Conversely, a wide corridor increases the premium for interbank transactions, encouraging banks to rely on bilateral markets or other short-term instruments before using central facilities. In stressed conditions, a wide corridor can amplify fragmentation: banks facing perceived counterparty risk may demand larger spreads, reducing market liquidity.
Causes, consequences, and nuances
Central banks choose corridor width based on objectives, the depth of the interbank market, and reserve management strategy. Deliberately widening the corridor can be a tool to allow market rates to move more freely or to discourage routine use of central facilities. It can also reflect imperfect reserve control in economies with volatile autonomous factors such as fiscal flows or external shocks. The consequences extend beyond technical market functioning: reduced interbank liquidity can raise funding costs for smaller banks, tightening credit for households and small businesses and amplifying regional disparities in lending. In many emerging markets, where interbank markets are thin and cultural or institutional trust levels vary, corridors operate differently than in advanced economies, requiring complementary measures like collateralized repo operations or liquidity-provision programs.
Understanding corridors therefore matters for policymakers and market participants alike: the design affects daily liquidity allocation, the effectiveness of policy transmission, and ultimately real economic outcomes through credit availability and borrowing costs.