The title compound, C(18)H(13)Cl(11), is an undecachlorinated commercial flame retardant. The asymmetric unit contains two independent half-mol-ecules. The complete mol-ecules are generated by crystallographic inversion symmetry, causing the terminal H atoms and one of the Cl atoms to be disordered equally over two sites in each mol-ecule. The central eight-membered rings are in chair-type conformations. In the crystal structure, there is a single weak inter-molecular C-H⋯Cl hydrogen bond.