Sam Christie and Aniruddha Rajan
Sudden contractions in credit supply can trigger and amplify recessions – a reality made painfully clear by the 2008 global financial crisis (GFC). However, quantifying these real economic effects is challenging. In this post, we demonstrate a novel way to do so using Granular Instrumental Variables (GIV), focusing on the UK mortgage market. The core idea is that we can exploit the market’s concentration to build up exogenous fluctuations in aggregate credit supply from idiosyncratic lender-specific shocks. Using our GIV, we find evidence that contractionary mortgage supply shocks can have quantitatively significant effects on the macroeconomy, causing persistent decreases in output, consumption, and investment, alongside increases in unemployment.
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