S&P Global Ratings late Wednesday lowered its rating on J.C. Penney Co. Inc. debt further into junk territory to B, saying that operational setbacks and the departure of Chief Executive Marvin Ellison "will make it harder for JCP to successfully improve" its performance. There's "heightened uncertainty around the company's strategy and path forward under new leadership," the ratings agency said. J.C. Penney said Tuesday that it is searching for a new CEO after Ellison left to become chief executive of Lowe's Cos. The retailer last week posted first-quarter earnings below expectations. Shares of J.C. Penney rose 0.4% in the late session after ending the regular trading day flat.