Mallinckrodt (MNK) is shaping a potential base despite triggering a sell signal. The stock slid more than 8% below a 130.35 buy point from a cup-with-handle base June 16, setting off a sell signal. It initially cleared the 130.35 entry May 28 in soft turnover. The stock hardly gained any ground before rolling over. Despite that, the stock remains in a box-like pattern in mostly mild volume.