Shares of Amazon.com Inc. AMZN, -2.96% slumped 3.1% in morning trading Friday, putting them on track for their first loss in seven sessions. Since the ecommerce and cloud giant's stock closed at a 2-year low of $2,082.00 on May 24, the stock had soared 20.6% over the past six sessions through Thursday, the best six-day performance since it ran up 23.0% over the six-day stretch that ended Feb. 5, 2015.