Shares of Michael Kors (KORS) were down after the retailer delivered a weak sales outlook for the coming year. Despite new store openings and a lower tax rate, the company still fell short of estimates for the fourth quarter. The retailer reported earnings of $0.90 per share, up from last year's numbers but missing analyst estimates of $0.91. Revenue came in at $1.04 billion, also falling short of predictions. It was the slowest revenue growth reported since the company went public. Despite strong profit increase, Michael Kors stock has now lost over half its value in the last year. Sales were up almost 18 percent from the previous quarter. However, the designer brand has opened 121 stores over the last 12 months, causing investor concern that the brand may be becoming over exposed.