Liberty Media Corp. (LSXMA, LSXMB, LSXMK, FWONA, FWONK, LLYVA, LLYVK) and audio entertainment company Sirius XM Holdings Inc. (SIRI), announced Tuesday that they have entered into definitive agreements whereby Liberty Media's Liberty SiriusXM tracking stock group will be combined with SiriusXM to create a new public company.