One hundred years ago, U.S. antitrust prosecutors broke down monopolies in meatpacking. But can they do it again?

Supermarket customers are paying more for beef than they have in decades during the coronavirus pandemic. But at the same time, the companies that process the meat for sale are paying farmers and ranchers staggeringly low prices for cattle.

Now, the Agriculture Department and prosecutors are investigating whether the meatpacking industry is fixing or manipulating prices.

The Department of Justice is looking at the four largest U.S. meatpackers — Tyson Foods, JBS, National Beef and Cargill — which collectively control about 85 percent of the U.S. market for the slaughter and packaging of beef, according to a person with knowledge of the probe. The USDA is also investigating the beef price fluctuations, Agriculture Secretary Sonny Perdue has confirmed.

Meatpackers say beef prices have spiked during the pandemic because plants are running at lower capacity as workers fall ill, so less meat is making its way to shelves. The four companies didn’t respond to requests for comment about the probes.