We consider an economy in which agents may or may not communicate with each other. Coalitions can form only between linked agents. We consider two cases: agents must communicate directly to be in the same coalition or in the second case indirectly. We consider the communication to be random. The economy may then be represented by a stochastic graph; the admissible coalitions are then stochastic and thus so is the core of an economy. We demonstrate that if the probability that agents are linked with each other does not tend to zero too fast as this number increases, then the probability that a coalition will form and block any non-Walrasian allocation tends to one, as the number of agents goes to infinity.