Yeah, the FTC and DOJ publish guidelines with thresholds, and you basically just follow them. E.g. https://www.ftc.gov/enforcement/premerger-notification-progr

Yeah, the FTC and DOJ publish guidelines with thresholds, and you basically just follow them. E.g. https://www.ftc.gov/enforcement/premerger-notification-program https://www.ftc.gov/enforcement/premerger-notification-progr... https://www.ftc.gov/enforcement/premerger-notification-program/statute-rules-formal-interpretations/premerger-introductory-guides https://www.ftc.gov/enforcement/premerger-notification-progr... There are like 10k+ mergers and acquisitions done in the US each year (ballpark). It requires real analysis to figure if something should be blocked (practically none have any real effect on anything and shouldn't be) and there are only so many folks at the regulators who can do that analysis (and honestly... they aren't good at it...).