Shadow banking entities have been repeatedly charged with the breaking up of the recent financial crises. This paper examines the contribution of the money market funds, an important part of the shadow banking entities, to the systemic risk in United Kingdom by using the CoVaR methodology (Adrian and Brunnermeier, 2016). Using a sample of 143 money market funds, continuously listed between 2005Q4 and 2013Q4, we investigate the impact of institutional corporate variables on the systemic risk. Our results show that liquidity mismatch increases the average systemic risk over the whole period, but decreases the risk during the Great Financial Depression. Crown Copyright (C) 2017 Published by Elsevier Inc. All rights reserved.