Acting in concert means two or more persons or companies working together with a common objective, usually to gain control or influence over a company.

Simple Meaning:

When people cooperate and make decisions together for the same purpose especially in buying shares or controlling a company they are said to be acting in concert.

Example:

If two investors agree to buy shares together to control a company’s management, they are acting in concert.

This term is commonly used in company law and takeover regulations.