  How can firms optimally negotiate bilateral contracts with each other in a
financial network? Every firm seeks to maximize the utility it gains from its
portfolio of contracts. We focus on mean-variance utilities, where each firm
has its own beliefs about the expected returns of the contracts and the
covariances between them (Markowitz, J. Finance 7(11), 1952). Instead of
revealing these beliefs, a firm may adopt a different negotiating position,
seeking better contract terms. We formulate a contract negotiation process by
which such strategic behavior leads to a network of contracts. In our
formulation, any subset of firms can be strategic. The negotiating positions of
these firms can form Nash equilibria, where each firm's position is optimal
given the others' positions.
  We give a polynomial-time algorithm to find the Nash equilibria, if they
exist, and certify their nonexistence otherwise. We explore the implications of
such equilibria on several model networks. These illustrate that firms'
utilities can be sensitive to their negotiating position. We then propose trade
deadlines as a mechanism to reduce the need for strategic behavior. At the
deadline, each firm can unilaterally cancel some or all of its contracts, for a
penalty. In our model networks, we show that trade deadlines can reduce the
loss of utility from being honest. We empirically verify our insights using
data on international trade between 46 large economies.
