American Tower is one of the largest global REITs and the leading independent owner, operator, and developer of wireless tower infrastructure. The core business is straightforward: American Tower owns tower structures, then leases space on those towers to wireless carriers — including AT&T, T-Mobile, and Verizon — who install their own antennas and equipment. The key economic driver is co-tenancy: when a second or third carrier leases space on an existing tower, incremental revenue drops almost entirely to the bottom line because most tower costs (ground rent, power, maintenance) are fixed. U.S. leases typically run 5–10 years with ~3% annual fixed escalators; international leases are generally CPI-linked. American Tower also owns CoreSite, a portfolio of 30 interconnection-focused data center facilities in major U.S. metros, where enterprises and cloud providers co-locate to access multi-cloud connectivity. New leasing activity in the tower business is driven by carrier amendments (adding or upgrading equipment) and co-locations (new carriers signing onto existing towers); the U.S. is currently in the capacity densification phase of the 5G cycle. American Tower operates across six segments: U.S. & Canada (~49% of revenue), Latin America (~15%), Africa & APAC (~13%), Data Centers (~10%), Europe (~9%), and Services (~3%). The company has been systematically exiting emerging market assets and redeploying capital toward developed markets — U.S. towers, Europe, and CoreSite — targeting developed markets at roughly 75% or more of unlevered AFFO. As a REIT, American Tower distributes at least 90% of taxable income as dividends and relies on debt and equity markets to fund growth.