After her not-universally-well-received exploration of her DNA, Elizabeth Warren has returned to what made her into a potential presidential candidate in the first place: needling big companies. She’s written angry letters this week about two of America’s largest and most controversial corporations, Amazon and Wells Fargo.

Warren joined Bernie Sanders in writing to Amazon chief executive Jeff Bezos about efforts the company made to warn employees about negative consequences of unionizing. Gizmodo published a 45-minute video that was shown to “Team Leaders” at Whole Foods locations. The video says plainly, “We do not believe unions are in the best interest of our customers, our shareholders, or most importantly, our associates. Our business model is built upon speed, innovation, and customer obsession—things that are generally not associated with union. When we lose sight of those critical focus areas we jeopardize everyone’s job security: yours, mine, and the associates.”

The letter came after Amazon committed to raising its minimum wage to $15, following a monthslong campaign from Sanders focused on the company’s wage and labor practices. “We write to express our alarm at recent reports that your company is distributing anti-union materials to Whole Foods managers that directs and encourages potentially illegal interference with the rights of thousands of workers,” Warren and Sanders said in the letter, according to the Washington Post. While companies are allowed to criticize unions and union organizing to their employees, they are not allowed to explicitly threaten to retaliate against employees who are organizing or trying to organize a union.

Warren’s Wells Fargo letter is vintage Warren. She came onto the national scene as a bankruptcy scholar and into national politics overseeing the post–financial crisis bank bailouts; more recently, her harsh questioning of former Wells Fargo chief executive John Stumpf about the company’s fake-accounts scandal was followed by his resignation a few weeks later.

This time, she wrote to Federal Reserve Chairman Jerome Powell saying that the bank shouldn’t be allowed to grow until Stumpf’s replacement, Timothy Sloan, leaves as well. She said Sloan was “deeply implicated in the bank’s repeated and egregious misconduct.”

Warren also called for Sloan to go a year ago, when, during a Senate hearing, she told him, “You should be fired,” noting how he used to boast of the company’s inflated sales numbers to investors.

Wells Fargo is currently restricted by the Federal Reserve from growing in size past $1.95 trillion in assets due to “widespread consumer abuses.”

Who’s next on the Warren letter writing campaign? Comcast? The Trump Organization? Probably not 23andMe.