After hours buzz: COST, YUMC & more

A man poses for a photo with the Wall Street bull sculpture between Broadway and Exchange Place in the Financial District of New York.
Andrew Harrer | Bloomberg | Getty Images
A man poses for a photo with the Wall Street bull sculpture between Broadway and Exchange Place in the Financial District of New York.

Check out the companies making headlines after the bell:

Costco shares tumbled nearly 2 percent after hours, despite the company posting higher-than-expected fourth-quarter earnings.

Yum China's stock increased 1 percent in extended trading after the company reported better-than-expected third quarter earning and CEO Micky Pant announced that he will step down on March 1. Meanwhile, parent company Yum Brands' stock slipped almost one percent after hours.

Shares of Navient rose more than 1 percent in the extended session, despite news that Rosen Law Firm announced it is investigating allegations that the company may have issued materially misleading business information to the investing public.

Amazon.com's stock slid slightly after hours. Earlier Thursday, Bloomberg reported that the company will test its own delivery service.