NEW YORK (AP) — Amazon.com Inc.'s fourth-quarter earnings roundly beat analyst expectations, sending the Seattle e-commerce giant's stock soaring 14 percent in aftermarket trading. Wedbush Securities analyst Michael Pachter said the lower-than-expected costs were related to flat fulfillment expenses — what the company spends on its distribution centers and deliveries — during the holiday season even though Amazon shipped 100 million more items. The company also spent less on marketing expenses since the launch of its new hardware like Fire TV and the Fire Smartphone are behind it. In a call with investors, Piper Jaffray analyst Gene Munster pointed out that over the past two years it has been a "little bit of a roller coaster" for Amazon's gross margin, a key metric that shows how big a percentage of revenue is spent on investing back into the company.