公私合作？中央银行资金和信贷供应（英）

Apublic-privatepartnership? Centralbankfunding andcreditsupply by Matthieu Chavaz, David Elliott and Win Monroe Monetary and Economic Department March 2026 BISWorking Papers are written by members of the Monetary and EconomicDepartment of the Bank for International Settlements, and from time to time by othereconomists, and are published by the Bank. The papers are on subjects of topicalinterest and are technical in character. The views expressed in this publication arethose of the authors and do not necessarily reflect the views of the BIS or its membercentral banks. This publication is available on the BIS website (www.bis.org). A Public-Private Partnership?Central Bank Funding and Credit Supply∗ Matthieu Chavaz†David Elliott‡Win Monroe§ March 12, 2026 Abstract Weexploit the surprise announcement and subsequent amendment of a centralbankfundingschemetotesthowpublicliquidityprovisionaffectscreditmarketoutcomes.Contrarytothenotionthatpublicliquidityisprimarilyasubstituteforprivateliquidity,banksthataremoreexposedtostressinprivatewholesalefundingmarketsuselesscentralbankfunding.Werationalisethispatternbyestablishingan“equilibriumchannel”ofpublicliquidity.Themereavailabilityofcentralbankfundingreducesthecostofprivatewholesalefunding.Thisstimulateslendingbybanksexposedtowholesalefunding,regardlessofwhethertheyactuallyusethecentralbankfunding.Usingasurpriseamendmenttothedesignofthescheme,weshowthatthe“stringsattached”tocentralbankfundinghelptoexplainwhyitisanimperfectsubstituteforprivatefunding. Keywords:Central bank funding, Mortgage lending, Bank funding risk. JEL classification:E52, E58, G21. 1Introduction Public authorities can improve credit market outcomes by supplying liquidity whenprivate liquidity supply is subject to frictions (Holmstr¨om & Tirole 1998). One real-worldtest for this idea is the large-scale provision of liquidity by central banks in response tostress in private wholesale funding markets. In that case, most obviously, banks can use public liquidity as asubstitutefor stressedprivate funding, and this can boost their lending to the real economy. However, substi-tution from private to public funding could have a range of side-effects. For instance, thetransfer of private risk to the public sector could create moral hazard (Bolton et al. 2009),and public funds could support bank activities other than real-economy lending. And ifreducing such leaks requires adding “strings attached”, this could make public fundingless attractive to banks and thus less effective at stimulating lending (Bernanke 2022). However, a less obvious possibility is that public liquidity acts as acomplement toprivate liquidity, e.g.because the mere availability of a public outside option helps toresolve frictions in private liquidity supply (Tirole 2012,Philippon & Skreta 2012). Suchan “equilibrium effect” could help to improve credit market outcomes without publicliquidity actually being used, thus mitigating the potential side-effects from substitutioninto public funding. The main contribution of this paper is to establish the existence, drivers, and conse-quences of this equilibrium effect. To do so, we exploit the surprise announcement of aBank of England funding scheme, which was launched in response to stress in wholesalefunding markets and offered banks access to long-term funding, conditional on banks’lending to households and firms.Exploiting confidential loan-level mortgage data, wequantify the impact of this announcement on credit supply via an equilibrium effect,while controlling for the impact via banks’ direct use of the public liquidity (“participa-tion effect”) that most research has focused on to date. Exploiting a subsequent surprisechange to the terms of the scheme, we then test how the conditionality of central bankfunding (“strings attached”) affects the scheme’s impact on credit supply. Overall, our results suggest that the equilibrium effect is the dominant channel through which central bank funding stimulates lending, and that this effect allows banks to enjoythe benefits of central bank funding while avoiding its costs.We establish four mainresults backing that conclusion. First, contrary to the notion that public liquidity is pri-marily a substitute for private liquidity, we show that banks more exposed to stressedwholesale funding markets areless likely to use the scheme.Second, we show thatbanks more exposed to stressed funding markets reduce mortgage rates by more afterthe announcement—irrespective of how much they use the scheme. While participationin the scheme also leads to lower lending rates, this participation effect is substantiallysmaller than the equilibrium effect in aggregate. Third, we show that the equilibrium ef-fect appears to operate through a reduction in perceptions of banks’ funding risk, ratherthan through an increase in their bargaining power in funding markets. Finally, using thesurprise change to the terms of the scheme, we show that the conditionalit