The law firm that successfully sued Apple and five major publishers for colluding to fix e-book prices in 2011 has now filed a class action suit against Amazon, accusing the company of colluding with the Big Five publishers to restrain price competition in the e-book market.

The suit, filed in the Southern District of New York on January 14 by Seattle-based firm Hagens Berman, comes a day after a Wall Street Journal article disclosed that Amazon was under investigation in Connecticut for potentially anti-competitive behavior in the e-book market.

The suit names only Amazon as a defendant. However, it labels each of the Big Five publishers—Hachette, HarperCollins, Macmillan, Simon & Schuster, and Penguin Random House—as “co-conspirators” in an alleged scheme to use various forms of a Most Favored Nations clause (MFN) to squelch consumer price competition and keep e-book prices artificially high.

“In violation of Section 1 of the Sherman Antitrust Act, Defendant and the Big Five Co-conspirators agreed to various anti-competitive MFNs and anti-competitive provisions that functioned the same as MFNs,” the complaint states. “Amazon’s agreement with its Co-conspirators is an unreasonable restraint of trade that prevents competitive pricing and causes Plaintiffs and other consumers to overpay when they purchase e-books from the Big Five through an eBook retailer that competes with Amazon. That harm persists and will not abate unless Amazon and the Big Five are stopped.”

Among the relief requested, the suit seeks monetary reimbursement for consumers who purchased e-books through Amazon’s competitors, damages, and injunctive relief that would require Amazon and the publishers to “stop enforcing anti-competitive price restraints.”

Hagens Berman was the first to sue Apple and five of the then six major publishers for e-book price-fixing in 2011, in a case that would eventually draw suits from a number of states and the Department of Justice. The five publishers settled their claims for some $166 million, while Apple lost at trial and paid out some $400 million to consumers.

Amazon had no comment on the lawsuit. All the publishers named in the filing had no comment as well.

This is a developing story and will be updated.