Learn › Sectors & Property Types · 4 min read

Cell Tower / Infrastructure REITs

How cell tower REITs lease the same site to multiple wireless carriers, and why mobile data growth has driven decades of demand

What infrastructure REITs own

This sector is built around communications towers — tall structures and rooftop sites that hold the antennas and equipment wireless carriers use to provide coverage. Towers themselves come in a few common forms — monopoles, lattice towers, and guyed towers — chosen based on height requirements, wind loading, and available land, while rooftop sites are more common in dense urban areas where a free-standing tower isn't practical. American Tower, Crown Castle, and SBA Communications are the best-known publicly traded tower REITs. Some companies in this category also own fiber networks and small-cell or distributed antenna systems, typically mounted on street-level poles or existing structures, which supplement traditional towers with denser coverage in urban areas. A tower's structural capacity also limits how many carriers and how much equipment it can ultimately hold, so engineering reviews are often required before adding a new tenant or additional equipment to an already-loaded structure.

How they make money

A single tower can be leased to several wireless carriers at once, similar in concept to leasing different floors of a building to different tenants, with each carrier paying to attach its own antennas and equipment. Tower companies typically don't always own the land beneath a tower outright; in many cases they hold a long-term ground lease with a separate landowner, paying rent for the site while collecting much larger rent from the wireless carriers using the tower itself — a favorable spread that's core to the business model. Contracts with carriers are typically long-term, running many years, and usually include built-in annual rent escalators, which gives tower REITs a relatively predictable, contracted revenue stream compared with property types that re-lease more frequently.

What drives demand

Growth in mobile data usage has been the sector's primary long-term driver, since carriers need more antennas and equipment, spread across more sites, to handle rising data traffic. Each new generation of wireless technology — most recently the rollout of 5G — has historically prompted carriers to add equipment to existing towers or lease additional sites. The number of wireless carriers actively competing in a market also affects how much leasing activity towers see over time. Some tower companies have also expanded internationally, since many emerging markets are earlier in their wireless network buildout than the United States and can offer another avenue for tower additions and new tenant leases over time. Emerging technologies, including satellite-based connectivity, are sometimes discussed as a long-term consideration for the industry, though traditional ground-based towers have remained the primary infrastructure for delivering everyday mobile service.

Key risks

Tower REITs depend on a small number of large national wireless carriers for most of their revenue, so customer concentration is a central risk — the financial distress of a major carrier tenant, or consolidation that reduces the number of carriers in a market, can matter a great deal to a landlord. Adding fiber and small-cell networks alongside traditional towers requires substantial upfront construction spending with revenue that can take longer to materialize than a traditional tower lease, and new sites of any kind generally require local zoning and permitting approval, which can slow deployment timelines. Building new towers or fiber routes ahead of committed leasing is capital-intensive, and returns depend on how successfully that new capacity eventually gets leased up to paying tenants.

Metrics that matter

Organic tenant billings growth — revenue growth from existing towers, excluding acquisitions — and the number of tenants per tower (often called co-location) are the sector's signature metrics, since adding another tenant to an existing tower is highly profitable for the landlord. Because rent escalators are typically fixed rather than tied to inflation or usage, a tower REIT's contracted growth rate is unusually easy to estimate in advance compared with sectors where rent resets depend on prevailing market conditions at each lease renewal. Long contract terms with escalators also make near-term revenue relatively visible, so the backlog and contracted-revenue disclosures in a company's earnings supplement are useful alongside standard same-store growth figures; see the glossary for definitions of these terms.

How this fits with the broader sector

This category is sometimes labeled "Infrastructure" rather than strictly "towers," since it can include other physical and digital infrastructure assets beyond wireless towers. It's a distinct sector from data center REITs, even though both benefit from rising data usage. Investors comparing this sector with others in the guide series should keep in mind that towers, fiber, and data centers all sit under the broad umbrella of "digital infrastructure," even though each has a distinct business model. Current infrastructure REITs, including American Tower, are listed on the infrastructure sector page; see the sectors overview for the rest of the series.

See it in the data: Infrastructure REITs → American Tower profile →

Research and education only — nothing here is investment advice. Figures such as the 90% distribution rule are general and can change; always confirm against a company's filings.