Working Paper No. 398
By Anne Wetherilt, Peter Zimmerman and Kimmo Soramäki
We model the unsecured overnight market in the United Kingdom as a network of relationships and examine how the structure has changed over the recent period of crisis. Using established network techniques, we find strong evidence of the existence of a core of highly connected banks alongside a periphery. We find that membership of this core expanded during the crisis and suggest that this is due to a few intermediate banks becoming more connected. The widened reserve target bands may have also had an effect, by partially alleviating the need to manage reserve accounts close to a target and therefore allowing banks to exercise more discretion in forming relationships. However, there is an asymmetry between borrowers and lenders in the overnight market, with borrowers more reliant on the most established of the core banks during the crisis.