Is there data to support the assumption that shares will rise when an activist takes a seat on the board? Not quite. In the 71 campaigns of the study, 46 sought board representation and 40 succeeded. Yet 16 companies that yielded to pressure to seat an activist on the board underperformed their peers. The study included the sad case of J.C. Penney, in which activist investor William Ackman's intervention did the company no favors. J.C. Penney was the worst performer in the study compared with peers and had the second-worst total-shareholder return.