The companies are under fire over claims they've grown too big and developed financial muscle that makes it impossible for small and medium-sized businesses to compete.
Even during the pandemic, their businesses are growing and tech stock prices keep rising. The committee launched its investigation on antitrust grounds to establish whether the companies are blocking the fair development of the market.
Lawmakers say the companies are either monopolies or oligopolies. Together, the four have a market cap of around $5 trillion -- close to Japan's national GDP. "Overwhelming" is the only word to describe them.
The CEOs stressed that competition is intense. "The retail market is extraordinarily large and competitive," said Bezos. "Amazon accounts for less than one percent of the 25-trillion-dollar global retail market, and less than four percent of US retail." He also pointed out that the company has created hundreds of thousands of jobs in the US.
Cook also highlighted the competition his firm faces. "The smartphone market is fiercely competitive, and companies like Samsung, LG, Huawei and Google have built very successful smartphone businesses," he said. "Apple does not have a dominant market share in any market where we do business."
Criticism within the industry
Although the hearing continued for around five hours, the CEOs appear to have fallen short of sweeping away the allegations leveled at them.
Roger McNamee was an early investor in Facebook but is now a fierce critic of the tech companies. "I believe they have had a very negative effect on innovation because they're monopolies and they drive things to produce value for themselves," he said.
"We have to consider the possibility that personal data is a human right, not an asset. And we need to think about moving the power away from corporations back to people when it comes to their personal data so that, at a minimum, corporations have to ask permission every time they want to use personal data or transfer it."
Marc Benioff, Chairman and CEO of Salesforce, one of the top IT companies, echoes the sentiment. "They don't care about taking care of the children," he said. "They only care about making money. We have to be aggressive with companies and hold them accountable for their role in society."
In Seattle, where Amazon's headquarters are located, affluent tech employees have driven rents sky high, beyond the means of others in the city.
Shirley Henderson used to live near the city center coffee shop that she manages, but as rents went up, she was forced to move out to the suburbs.
"We are one of the epicenters of gentrification in the neighborhood," she says. "It's definitely put a huge burden on people in various neighborhoods across the city as they can no longer afford to live in communities that they've spent their entire lives in."
Seattle's city council has approved a new tax for the biggest businesses and their highest earners, including Amazon. The revenue will initially be used to fund coronavirus relief but will eventually go toward addressing housing and homelessness in Seattle.
"If you're a massive, wealthy corporation like Amazon or Boeing or Microsoft, actually you pay very little taxes and sometimes no taxes at all effectively," says Kshama Sawant, a Seattle council member who supported the bill. "So when we look at these measures that are being taken by the tech companies, we recognize that they are a very, very tiny fraction of what they actually should be doing."
The tech titans have had their say. Now the Congressional committee members will have theirs, in the form of a report they plan to issue that could recommend new checks on the power and scale of the big four. But in the meantime, the pandemic is only helping them grow.