At a moment when regulators, politicians and consumers are railing against companies getting too big, one behemoth has been growing under the radar: Walmart.The big picture: Walmart already had its turn as the corporate villain in the 1980s. Now, as tech companies bear the brunt of the scrutiny, the retail giant is amassing wealth — earning $514.4 billion in revenue, the most of any company on Earth, in 2018.What's happening: "I don't think anyone is paying attention to Walmart," says Sally Hubbard, a director at the Open Markets Institute and a former assistant attorney general in New York's antitrust bureau. "It's just not on people’s minds because it isn’t considered the way of the future. ... The government sees brick and mortar as more of a dying industry."But Walmart isn't going anywhere. It has transformed into a 21st-century company that's doing everything Amazon is doing — and it's neck-and-neck with Amazon in a few high-tech areas that are considered the tech giant's home turf, like drone delivery and same-day shipping.Investigators are under intense political pressure from lawmakers and consumers to do something about Big Tech, says Hubbard. But "the political pressure just isn't there to investigate Walmart. The places where Walmart has large grocery market share are not places where policy activists live."Amazon is new to the U.S. grocery business, of which Walmart already owns 13%.In many parts of America, Walmart's dominance is far more pronounced. The retailer has more than 50% market share in 203 cities and towns, and more than 70% in 38 of those places, per a recent report from the Institute for Local Self-Reliance (ILSR). Many of these towns are among the most economically distressed in the nation."No other grocer in the history of the country has ever had this kind of market share," says Stacy Mitchell, co-director at ILSR, a nonprofit research and advocacy group that opposes concentrated economic power.When it comes to all U.S. retail spending, Walmart takes 8.9% and Amazon 6.4%.Jeff Bezos has become the American billionaire archetype. But also consider the Walton family of Walmart fortune: six members of the family have more wealth than the bottom 41% of Americans.What to watch: Not only is Walmart avoiding the antitrust spotlight, but it is also helping fuel the techlash against its competitors.The Free and Fair Markets Institute, which called itself a "grassroots campaign" to topple Amazon, is funded by Walmart, reports WSJ.Walmart is also part of the Retail Industry Leaders Association that has written to the Federal Trade Commission and the Justice Department with concerns that Amazon and Google stifle competition, the LA Times reports.Worth noting: A major driver of the global antitrust probes into Amazon is the fact that it simultaneously operates as an e-commerce platform and an individual seller — it's the mall, but it also has its own store within the mall, in the best location. Walmart's online platform isn't nearly as powerful as Amazon's. "When we ask sellers who are fed up with Amazon why they don't switch to Walmart.com, they say the volume just isn't there," Hubbard says.The bottom line: "The fad to hate Walmart has been overshadowed," says Eleanor Fox, an NYU antitrust law professor.