5 Biggest Private Security Companies in the World

4. ADT Inc.

2021 Revenue: $5.31 billion

ADT Inc., formerly known as the ADT Corporation, is an American company that provides residential, small, and large business electronic security, fire protection, and other related alarm monitoring services throughout the United States. With almost a century and a half of experience of providing comprehensive security solutions to over 8 million customers throughout the US, ADT is arguably one of America’s oldest home and business security providers.

In recent years, the company has been venturing into other sectors as well. In November 2021, ADT announced an agreement to acquire Sunpro Solar, a residential rooftop solar power contractor, for $160 million in cash. The company was rebranded as “ADT Solar” and operates as a wholly owned subsidiary of ADT Inc.