Amazon is mentioned on earnings calls more than any other company, and rarely as an ally. With good reason, too: it has a history of aggressively competing on price until a rival gives up.
Now regulators are turning their eyes on the company. Last week, Margrethe Vestager, the European competition commissioner who has devoted much of her time to snapping at the heels of Apple and Google in recent years, said she was opening a preliminary investigation into whether Amazon unfairly uses the data it collects about independent sellers who use its website to identify opportunities to beat them with cheaper goods from its own Amazon Basics line.
The practice, known as predatory pricing, was the main argument for antitrust action against Amazon by US lawyer Lina Khan in a widely shared article last year.
Vestager was keen to express that she was merely sounding out retailers who use Amazon's website, and had made no decision on whether to open an investigation, but the news was still a big moment: the first real test of Amazon's growing power.
The company has evaded much antitrust scrutiny so far for a simple reason: it is not a monopoly in the classic sense.
Despite its size, its sales in the US remain below the grocery giants Walmart and Kroger; in the UK, the Big Four supermarkets have higher revenues, and it has less than a third of online shopping revenues.
Consumer harm has been relatively hard to prove, too: there is little evidence of price-gouging and shoppers still have plenty of alternative places to shop online - at least today. Amazon regularly tops lists of most popular brands.
On the face of it, Vestager's concern - that the company is being unfair in introducing competitive, cheaper products - may find little popular support. Who doesn't like cheap, reliable batteries and suitcases?
There are other reasons people disagree with Amazon, of course - its aggressive tax avoidance and stories of poor treatment and low wages for its employees and contractors do not endear it to many.
Bezos's US$158 billion ($237.8b) wealth in the face of such criticisms illustrates to many the inequalities that the modern economy allows.
But are shoppers worse off? It is hard to see much evidence of this. The concern with predatory pricing is that competition gets erased, but search Amazon for iPhone chargers and you will find thousands of alternatives to Amazon's own products.
Instead, it seems that most antitrust concerns centre on fear. The company's size, not its behaviour, is why so many feel distinctly uncomfortable with it.
As much as the company seems to benefit its customers, concentrating so much power in one organisation can simply feel uneasy to many.
Last week, a company press conference in Seattle showed more evidence of this. Amazon made a major push into the smart home, unveiling a line of Amazon-branded clocks, microwaves and plugs that connect to its Alexa voice control system.
The event painted a picture of a life in which Amazon arranges your meals, controls your house and automatically orders your groceries, a vision that could be seen as either effortlessly convenient or dystopian, or perhaps both.
Being big is not illegal, but that does not mean it won't create its own problems for Amazon.
