The title molecule, C₂₇H₂₄O₉, was formed via a transannular electrophilic addition of a putative cyclotriveratrylene triketone and is made up of an anthrone and an isobenzofuranone ring that are connected via one C atom to form a spiro compound. The anthracene and isobenzofuranone ring systems of the spiro compound are both essentially planar and perpendicular to each other, with an angle of 89.90 (2)° between them. The rigid molecule crystallizes with large voids of 598.7 ų, or 21.5% of the unit-cell volume, that are partially filled with unmodelled disordered solvent molecules. The voids stretch as infinite channels along the [101] direction. The packing of the structure is partially stabilized by a range of weak C—H...O hydrogen bonds and also by C—H...π interactions. No significant π–π interactions are present in the crystal structure.