RIM is close to a decision on stripping its co-chief executives of their other shared role as chairman of the board, The National Post newspaper said, a change that could meet a key demand from angry and disillusioned investors. The Post’s sources said Barbara Stymiest, currently an independent member of RIM’s board, is leading the race to replace Mike Lazaridis and Jim Balsillie in the chairmanship. RIM shares jumped more than 7 percent on the news. But some analysts doubted Stymiest, if named to the chairmanship, would actually assume the transformational role that activist shareholders are calling for.