Most Valuable U.S. eCommerce Companies 2024: Key Insights . Most Valuable by Market Cap: Amazon.com, Inc., with a market cap of US$1.56 trillion, is the most valuable U.S. eCommerce company, significantly leading in both market size and value.? Revenues of the Most Valuable: In terms of revenues, Amazon.com, Inc. stands out again with over US$513 billion in 2022, followed by other major players such as Coupang, Carvana and Wayfair.? Amazon Dominates: Top 3...