Amazon.com Inc. shares skyrocketed in after-hours trading Thursday after the e-tailing giant reported fourth-quarter diluted earnings per share of $27.75, results which included an $11.8 billion gain from its investment in Rivian Automotive Inc., the electric vehicle maker that completed an initial public offering in November and that has a contract with Amazon to build 100,000 delivery vans for the Seattle-based e-tailer. Amazon (NASDAQ: AMZN) reported net income of $14.3 billion in the fourth quarter, compared with $7.2 in net income, or $14.09 per diluted share, in the fourth quarter of 2020.