The big announcement this morning that BP Plc has sold its Texas City refinery to Ohio-based Marathon Petroleum Corp. (NYSE: MPC) barely moved the needle on its share price, while Marathon got a bump of more than 5 percent. BP (NYSE: BP) shares were down less than half a percentage point late Monday morning. Speculation has run high about the details of the $2.5 billion deal, which the Financial Times hinted at in September. The large, complex refinery is complicated by a storied history. An explosion…