Policymakers around the world call for more competition in the banking sector. One prerequisite to achieving this is customer mobility. Despite its policy relevance, surprisingly little is known about consumers' bank switching behaviour. We show that the principal reasons to stay at one's bank are a good bank-customer relationship, practical barriers, and the perception that there is not much benefit in switching. Moreover, we find that the reported propensity to switch varies across banking products. For the main current and savings accounts, this propensity is most strongly related to the bank-customer relationship, while for mortgage loans it is especially linked to switching experience. These findings have important implications for antitrust policy; they provide an argument against using a cluster-based legal standard for the analysis of competition and in favour of a disaggregated approach. Regarding the effectiveness of hypothetical policy initiatives to lower switching barriers, we find that the reported switching propensity with current accounts is higher in the case of account number portability, while more knowledge of the existing switching service has no significant effect. Lastly, scenario analysis shows that a policy of allowing new foreign banks to enter the savings market is less promising for enhancing mobility than a policy that increases the number of domestic players.