Before revision:  Here, we analyze the dynamics of real interbank networks at a daily temporal resolution. While daily networks have been flexibly changing their structure from day to day, entailing entries and exits of banks, we discover explicit dynamical patterns that have been surprisingly stable over time even amid the global financial crisis. The emergence of these dynamical patterns is accurately reproduced by a model, in which banks' demand for trading follows a random walk .
After revision:  Here, we uncover fundamental dynamics of interbank networks by seeking the patterns of daily transactions between individual banks. We find stable interaction patterns between banks from which distinctive network-scale dynamics emerge. In fact, the dynamical patterns discovered at the local and network scales share common characteristics with social communication patterns of humans. To explain the origin of "social" dynamics in interbank networks, we provide a simple model that allows us to generate a sequence of synthetic daily networks characterized by the observed dynamical properties .