  A minimal stochastic dynamical model of the interbank network is introduced,
with linear interactions mediated by an integral of recent variations. Defining
stress as the variance over the banks' states, the interaction correction to
the stress expectation is derived and studied on the short-medium timescale in
an expansion. It is shown that, while different interaction matrices can
amplify or absorb fluctuations, on average interactions increase the stress
expectation. More in general, this analytical framework enables to estimate the
impact of uncertainty about financial exposures, and to draw conclusions about
the importance of disclosure.
