Here is likely what you’re referring to. Above ~~$75M it has to be declared and then you are subject to review. https://en.m.wikipedia.org/wiki/Hart–Scott–Rodi

Here is likely what you’re referring to. Above ~~$75M it has to be declared and then you are subject to review. https://en.m.wikipedia.org/wiki/Hart–Scott–Rodino_Antitrust_Improvements_Act https://en.m.wikipedia.org/wiki/Hart–Scott–Rodino_Antitrust_...