The nature of the excitations in the pseudogap regime and their relation to superconductivity remain core issues in cuprate high-T c superconductivity. Here, using resonant inelastic x-ray scattering, the authors find that high-energy excitons in optimally-doped Bi2Sr2CaCu2O8+δ are enhanced by the onset of superconductivity, an effect possibly explained in terms of electron fractionalization.