Women's clothing and shoe chain The J Jill Group Inc on Thursday said it swung to a third quarter loss on the back of a poor performance by its merchandising and product development business, the president of which has just resigned. The Massachusetts-based firm posted a net loss for the quarter ended September 27 of $2.9 million or 15 cents per share, versus net income of $3.6m, or 18 cents per share, in the year-ago period.