Simulation of galactic halo formation. Blue (red) dots represent the positive (negative) mass particles. Upper image: Starting conditions, representing a Hernquist positive mass spherical galaxy embedded in a uniform distribution of negative masses. Lower image: Final state, exhibiting a nonspherical halo of enhanced negative-mass density around the galaxy. The galactic center of mass is initially at rest. In the final frame it is moving towards the left of the image. We note that the figure is represented in a 3D isometric perspective. Apparent particle densities may be misleading due to projection effects.