Shares of SiriusXM (SIRI 12.15%) were rallying big today, up 12.3% as of 1:37 p.m. ET.While most of the market was up today on the back of a better-than-feared personal consumption price index report, beaten-down Sirius got an extra oomph thanks to Warren Buffett and his investing staff at Berkshire Hathaway (BRK.A 1.37%) (BRK.B 0.86%), which disclosed an increased stake in Sirius last night.Buffett & Co. try to bottom-tick SiriusOn Thursday night, Berkshire Hathaway filed a Form 4 with the Securities and E ...