NEW YORK (AP) - Shares of J.C. Penney Co. plunged a day after the department-store chain reported massive losses and a nearly 30 percent drop in revenue in its fiscal fourth-quarter period. The results, which were much worse than Wall Street expected, cap off a full year of steep losses and sales drops since CEO Ron Johnson launched a turnaround plan that included getting rid of most the 600 or so discounts the chain used to offer each year in in favor of everyday low prices. Penney reported on Wednesday after the markets closed that it widened its quarterly loss to $552 million, or $2.51 per share. Revenue fell 24.8 percent to $12.98 billion. On Thursday, its shares fell 19 percent, or $3.98, to $17.18. Shares have dropped 60 percent since early last year.