Three corporate guilty pleas in a long-running Justice Department antitrust investigation sent white-collar lawyers scrambling Wednesday to figure out what it might portend for other companies, and for individual executives.

San Francisco-based federal prosecutors joined their superiors in a Washington, D.C., press conference to announce big fines for price fixing in the LCD computer and television screen industry. South Korea’s LG Display got hit hardest, agreeing to pay $400 million in what the government described as the second-biggest antitrust fine ever.