Cells were fixed with 1% formaldehyde for 10 minutes. After cell lysis, chromatin was sonicated using a Branson needle-tip sonicator. Prior to immunoprecipitation, Protein G beads were coupled with unique antibody identifying oligonucleotides and the corresponding antibodies. Protein-chromatin complexes were isolated from prepared chromatin with a heterogenous pool of these oligonucleotide-labeled, antibody-coupled Protein G beads.  After immunoprecipitation, DNA ends were repaired and dA-tailed to generate a protruding 3' A. Split-and-pool barcoding was performed to associate IP'd DNA molecules with the antibody-identifying oligonucleotide on the same Protein G bead. Crosslinks were reversed, the DNA was isolated and the DNA was amplified 8-12 cycles using standard Illumina library prep (dual index). The PCR products were purified using SPRI beads and gel cut.