This paper provides a new index of money market and bank lending interest rates in Spain for 1900–1935. New archival evidence reveals a structural change in market interest rates vis-à-vis the official rates charged by the Banco de España (BdE). Before 1914, the BdE rate operated as a ceiling to market rates. The outbreak of the First World War caused market rates to soar and the BdE rate started operating as a floor, as bank liquidity started depending on the BdE. This was accompanied by new banking legislation introduced in 1921, which changed the collateral framework through which the BdE lent to banks. The resulting interest rate index illustrates the persistent impact of financial deglobalisation caused by the outbreak of the War.
