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A presidential candidate is making a move on big tech. Democratic Sen. Elizabeth Warren on Friday called for "big, structural changes" to break up tech giants like Amazon, Google and Facebook.

"Today's big tech companies have [too much power over] our economy, our society, and our democracy," Warren wrote in a blog post. "They've bulldozed competition, used our private information for profit, and tilted the playing field against everyone else. And in the process, they have hurt small businesses and stifled innovation."

Warren said big tech companies use mergers to swallow competition and sell products on their own e-commerce platforms, which hurt smaller businesses' opportunities to succeed. Weak antitrust enforcement also resulted in "a dramatic reduction" in competition and innovation in the tech industry, according to Warren's blog post.

To prevent the tech sector from abusing monopoly power, Warren suggested passing laws that prevent large e-commerce platforms (with global annual revenue of $25 billion or more) from owning both the platform and any sellers on it. Smaller platforms (with global annual revenue of between $90 million and $25 billion) can sell things on their own platforms, but will have to comply with rules of fair competition.

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Warren also promised that her administration would appoint regulators to reverse illegal and anticompetitive mergers in the tech sector, such as Amazon's Whole Foods and Zappos acquisitions, Facebook's buyout of WhatsApp and Instagram, and Google's Waze, Nest and DoubleClick acquisitions.

President Donald Trump has also worried about the level of competition in the tech sector, commenting in August that tech companies are in a "very antitrust situation." Trump, though, was more worried about tech companies controlling what people can and can't see on the internet. Federal Trade Commission nominees in February said they would be open to considering antitrust action against against tech firms.

Facebook and Amazon declined to comment. Google didn't immediately respond to a request for comment.