In an amended complaint, the commission seeks to bolster its allegations that Facebook has abused a monopoly position in social networking.
The commission is committed to "enforcing the antitrust laws against monopolists, including in high-technology industries."
A witness at a Senate hearing compared the companies' control over their platforms to the "behavior of the robber barons."
Facebook, Google, Amazon and Apple "have become the kinds of monopolies we last saw in the era of oil barons and railroad tycoons."
The court says iPhone users are eligible to sue Apple for overcharging them for apps sold in the App Store.
