We study non planar corrections to the spectrum of
operators in the N = 2 supersymmetric Yang Mills
theory which are dual to string states in the maximally supersymmetric ppwave background with a compact
lightcone direction. The existence of a positive
definite discrete lightcone momentum greatly
simplifies the operator mixing problem.
We give some examples where the contribution
of all orders in nonplanar diagrams can be
found analytically.
On the string theory side this corresponds
to finding the spectrum of a string state
to all orders in string loop corrections.
