In the title compound, C18H14O2S, the system of four fused rings is almost planar (r.m.s. deviation = 0.022 Å). The C atoms of the methoxy groups deviate from the mean plane of the ring system by 0.373 (2) and −0.104 (2) Å. In the crystal, very weak aromatic π–π stacking interactions [shortest centroid–centroid separation = 3.9286 (10) Å] may help to establish the packing.
