  Boards of large corporations sharing some of their directors are connected in
complex networks. Boards are responsible for corporations' long-term strategy
and are often involved in decisions about a common topic related to the belief
in economical growth or recession.
  We are interested in understanding under which conditions a large majority of
boards making a same decision can emerge in the network. We present a model
where board directors are engaged in a decision making dynamics based on "herd
behavior". Boards influence each other through shared directors.
  We find that imitation of colleagues and opinion bias due to the interlock do
not trigger an avalanche of identical decisions over the board network, whereas
the information about interlocked boards' decisions does. There is no need to
invoke global public information, nor external driving forces.
  This model provides a simple endogenous mechanism to explain the fact that
boards of the largest corporations of a country can, in the span of a few
months, take the same decisions about general topics.
