NEW YORK (AP) — Shares of J.C. Penney Co. fell nearly 11 percent after the department store operator warned that its sales last month were weaker than expected and it cut its outlook for a key sales measure for the current quarter.

The warning overshadowed the company’s unveiling of a strategy at its analysts’ meeting Wednesday that the retailer said would boost sales by $2.55 billion over next three years. It would do so by improving the productivity of its stores’ home department, expanding e-commerce and sprucing up key areas like jewelry, shoes and handbags.