A press conference held Tuesday in California will announce a major class-action lawsuit against the UFC, according to a press release and multiple sources close to the suit.

The sources asked for anonymity because they were not authorized to publicly discuss the situation.

The press conference takes place at 4 p.m. ET (1 p.m. PT local time) at Hyatt Place in San Jose and will feature “professional MMA fighters and their attorneys.” A list of plaintiffs names and details on the lawsuit will be revealed at the media event, the release states.

No further information is given on the lawsuit, but according to a report from BloodyElbow.com, the suit alleges that UFC parent company Zuffa violated antitrust laws by using its industry-leader status to cripple the free market.

A UFC representative was not immediately available for comment when contacted by MMAjunkie.

To date, the most significant antitrust allegations against Zuffa came from the Federal Trade Commission, which investigated the fight promotion in 2011 and 2012 and took no action, though it did not rule out future action.

Check back with MMAjunkie for details on the suit and the participants, which. according to sources, include active UFC fighters.

For more on the UFC’s upcoming schedule, check out the UFC Rumors section of the site.