Sen. Amy Klobuchar (D-Minn.) on Tuesday introduced legislation that would strengthen the ability of antitrust enforcement agencies to go after industry giants.

The Anticompetitive Exclusionary Conduct Prevention (AECP) Act, co-sponsored by Sens. Cory Booker (D-N.J.) and Richard Blumenthal (D-Conn.), would amend the 1914 Clayton Antitrust Act.

It would shift the burden of proof in the hundred-year-old law so that companies with a market share over 50 percent, or "significant market power," have to prove that exclusionary conduct does not cause “an appreciable risk of harming competition.”

The legislation would also allow both agencies tasked with antitrust investigations, the Department of Justice (DOJ) and the Federal Trade Commission (FTC), to dole out civil penalties of up to 15 percent of the company's revenues for Clayton violations.

The bill also eliminates the need in some cases for claimants to prove a relevant market before establishing liability under antitrust laws. And it limits the ability of courts to imply immunity for certain anticompetitive conduct based on federal regulations.

“We have a major monopoly problem in this country, which harms consumers and threatens free and fair competition across our economy. Companies need to be put on notice that exclusionary behavior that threatens competition cannot continue,” Klobuchar said in a statement.

“Our legislation will deter anticompetitive abuses, helping to protect the competitive markets that are critical to ensuring fair prices for products and services, spurring innovation, and preserving opportunity for American entrepreneurs," she said.

The legislation comes as both the DOJ and FTC conduct antitrust investigations into major tech companies.

In a Senate Judiciary antitrust subcommittee hearing on competition in digital markets on Tuesday, experts said Klobuchar's bill would make those investigations more effective.

"The legislation ... introduced today would be a great first step to try to create new balances in antitrust enforcement, create new streamlined opportunities for enforcers to show their faces," said Gene Kimmelman, senior adviser at nonprofit Public Knowledge.

Other experts at the intersection of tech and antitrust are concerned that the bill doesn’t go far enough.

“While I think these changes are necessary and they represent a step in the right direction, they ultimately will be insufficient,” Daniel Hanley, a policy analyst at the Open Markets Institute think tank, told The Hill.

“The technology companies have market dominance. Litigation for them is the cost of doing business.”

Sarah Miller, the executive director of the newly formed American Economic Liberties Project, said in a statement the bill is insufficient in the face of the scale of monopolies in tech.

“The bill is riddled with loopholes, like creating vague standards that corporations' well-heeled lawyers will exploit. Congress needs to make clear rules, not give vague instructions to judges to determine when a monopolist is acting improperly,” Miller said.

“By relying on vague terms like “risk of harming competition,” open-ended standards for identifying law-breaking like “the totality of the circumstances,” and “baseless or even bad faith,” the Anticompetitive Exclusionary Conduct Prevention Act talks big and accomplishes little.”