Amazon Cracks Fortune 500 List's Top Ten, A First Inc. (AMZN) has reached a new milestone: it finally cracked the top ten on the annual Fortune 500 list of the biggest U.S. companies based on revenue that was released earlier this week.

The Seattle, Washington-based e-commerce giant landed in eighth place, four spots higher than in 2017. Fortune cited its “remarkable growth run” for moving up in the rankings; Amazon's sales have increased around $70 billion in two years time. “Amazon’s enormity stems from its role as the largest U.S. digital retailer, the fastest-growing part of the market,” wrote Fortune. “Two other major factors drive the company’s growth: Expansion abroad to markets like India and the rise of Amazon Web Services, the company’s market-leading online storage and service operation.” With Amazon spending heavily to improve delivery times, provide more entertainment and equipped warehouses with robots, the company is set to grow more. Both AT&T Corp. (T) and General Motors Co. (GM) trailed Amazon in the rankings coming in at ninth and tenth, respectively. (See more: Amazon, New Tech Powerhouse, Losing Executives.)

Walmart Still The Largest U.S. Company

While Amazon is making inroads on the Fortune 500 List and is leading in e-commerce, its rival Walmart Inc. (WMT) is still larger, topping the list for the sixth straight year in a row. Fortune credited the company with exiting less productive parts of its business to better focus on growth areas. “Its Walmart business in the U.S. is transforming its website into an online mall offering a slew of brands and expanding its grocery delivery, while the shuttered Sam’s Clubs will be repurposed as e-commerce distribution centers to speed up delivery,” wrote Fortune. “Meanwhile, Walmart is making big moves in both China and India, looking to rev up international growth again.” Rounding out the top five were Exxon Mobil Corp. (XOM), Berkshire Hathaway (BRK.A), Apple Inc. (AAPL) and United Health Group Inc. (UNH). (See more: How Jeff Bezos Got to Be the World's Richest Man.)

Tech Companies The Most Valuable

From a valuation perspective, the four most valuable companies were Apple, Alphabet Inc. (GOOG), Microsoft Corp, (MSFT ) and Amazon. Berkshire Hathaway was in fifth place. Apple was the most profitable company on the list, followed by Berkshire Hathaway and AT&T, noted Fortune. Fortune raised the revenue threshold to make it on its annual list 6% to $5.4 billion.

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