  An increase in theoretical precision of Monte Carlo event generators is
typically accompanied by an increased need for computational resources. One
major obstacle are negative weighted events, which appear in Monte Carlo
simulations with higher perturbative accuracy. While they can be handled
somewhat easily in fixed-order calculations, they are a major concern for
particle level event simulations. In this article, the origin of negative
weights in the S-MC@NLO method is reviewed and mechanisms to reduce the
negative weight fraction in simulations with the Sherpa event generator are
presented, with a focus on V+jets and tt+jets simulations.
