We develop a single-period model for a large economic agent who trades with
market makers at their utility indifference prices. A key role is played by a
pair of conjugate saddle functions associated with the description of Pareto
optimal allocations in terms of the utility function of a representative market
maker.Comment: Shorten from 69 to 30 pages due to referees' requests; a part of the
previous version has been moved to "The stochastic field of aggregate
utilities and its saddle conjugate", arXiv:1310.728