American Tower Corporation

What does it do?

American Tower owns and rents out the physical cell towers that make your phone calls and mobile data work. Think of them like a landlord — except instead of apartments, they own over 220,000 towers and antenna sites around the world. Wireless carriers like AT&T, Verizon, and T-Mobile pay American Tower to attach their equipment to these towers. One tower can have multiple carriers paying rent at the same time, which is the key to the whole business.

How does it make money?

American Tower makes almost all of its money from long-term lease agreements with mobile carriers who rent space on its towers. These leases typically run 5–10 years with automatic rent increases built in — usually around 3% per year — giving the company highly predictable, recurring revenue. In its latest full year, American Tower brought in $10.6 billion in revenue, up from $10.1 billion the prior year. Because one tower can serve multiple tenants simultaneously, adding a new tenant costs very little but generates significant extra profit.

Why do investors care?

The 5G buildout is the central growth story here — carriers need to densify their networks with more equipment, and that equipment has to go somewhere. American Tower also has significant exposure to fast-growing emerging markets in Africa, Latin America, and India, where mobile connectivity is still expanding rapidly. For the thesis to work, carriers need to keep spending on their networks and interest rates need to stay manageable, since tower companies carry meaningful debt to fund their infrastructure. The company's long-term contracts and inflation-linked rent escalators give it a layer of protection most businesses don't have.