Cell Towers and Adjacent Digital Infrastructure

Introduction

Cell towers are not data centers, but they sit in the same coverage scope, and for good reason. Both are real estate wrapped around digital infrastructure, both are valued on funds from operations rather than earnings, and both are increasingly converging as the network edge moves closer to where compute happens. A real estate banker covering data centers will inevitably field questions about the tower REITs, and the two asset classes share enough economic DNA that understanding one sharpens the read on the other. The single most important idea in towers is operating leverage: a tower's cost base is largely fixed, so each additional tenant added to it is almost pure profit.

A cell tower is a simple physical asset, a steel structure on a parcel of leased or owned land, but its economics are unusually powerful because of how tenants stack onto it. Carriers lease vertical space and ground area to hang their antennas, and once the tower exists, the marginal cost of adding a second or third carrier is minimal while the rent is nearly all incremental profit.

The contracts reinforce the stability. Tower leases run long, typically with 3% annual escalators and only 1% to 2% annual churn, producing a remarkably predictable, growing cash-flow stream. Like other REITs, tower companies are valued on AFFO rather than net income, generally trading at 20 to 25 times AFFO, a premium multiple that reflects the durability and built-in growth of the income. That AFFO-based valuation follows the same logic as the broader explanation of how REITs trade on FFO and AFFO multiples.

Tenancy Ratio

The average number of tenants per tower across a portfolio. Because a tower's costs are largely fixed, the tenancy ratio is the key driver of returns: moving from one tenant to two or three transforms the economics, so raising the ratio through colocation is the core value lever in the business.

One real-estate nuance sits literally underneath the model: most towers do not own the land they stand on. The typical tower is built on a ground lease, where the landowner leases the footprint to the tower company, which owns the steel and the antennas on top. That split has spawned its own sub-industry of ground-lease aggregators, firms such as AP Wireless, Landmark Infrastructure, and Unison Site Management, that buy up the land under towers to collect the ground rent as a long-duration, inflation-linked income stream. The tower REITs increasingly buy the land beneath their own towers for the same reason, converting a recurring lease expense into owned real estate and removing the risk that a landlord refuses to renew or demands a steep increase.

The United States tower market is an oligopoly. American Tower (AMT), Crown Castle (CCI), and SBA Communications (SBAC) together control more than 70% of US towers, a concentration that gives them durable pricing power against their tenants. Towers fall on the boundary of what counts as real estate, a boundary case discussed in the real estate value chain, but their REIT structure and rent-based model place them squarely in the digital-infrastructure conversation.

The other side of that concentration is on the demand side. All three derive the bulk of their US revenue from the same three wireless carriers: AT&T, Verizon, and T-Mobile. SBA drew about 66% of its US revenue from the three in 2024, and Crown Castle's carrier revenue has run around 75%. That is a mirror image of the hyperscaler tenant concentration in data centers: a handful of enormous, creditworthy tenants providing both stability and concentration risk. Carrier wireless capital spending matters enormously to the towers, and it slid to about $32.4 billion in 2024, the lowest in six years, even as tenancy ratios kept climbing.

The three are no longer pursuing the same playbook, and the strategic split is the clearest signal of where each sees the future:

American Tower is also the most globally diversified of the three, with large tower portfolios across Latin America, Africa, and Europe, alongside a historically major India business it has been exiting. International towers offer faster growth but carry currency and emerging-market risk, which is part of why the market tends to value the US portfolio at a premium to the international one. For a cross-border banker, the towers are a reminder that digital infrastructure is a global asset class, not a purely American one, and that the same operating-leverage economics apply whether the tower sits in Texas or Brazil.

The macro tower is only the top layer of wireless real estate. As 5G pushes carriers to densify their networks, a second layer has grown beneath the roughly 349,000 US macro towers: small cells and distributed antenna systems, fed by fiber. The United States is projected to reach a total of 900,000 to 1,000,000 small cells by 2030, roughly three times as many nodes as there are towers.

Small Cell

A low-power radio node mounted on a streetlight, utility pole, or building, far smaller than a macro tower, that adds network capacity in dense areas a tower cannot efficiently serve. Small cells connect back to the network through fiber, which is why fiber ownership and small-cell deployment are economically inseparable, and why an operator in one is usually in both.

The economics are the opposite of the macro tower's, and that difference explains the strategic split among the operators. A macro tower spreads a largely fixed cost across two or three tenants and throws off the powerful operating leverage described above. Small cells and the fiber that feeds them are capital-intensive, often single-tenant, and slower to reach scale, so their returns have disappointed relative to towers. That gap is precisely why Crown Castle chose to retreat from fiber and small cells back to pure macro towers, the reversal detailed in the next section, while specialist fiber and edge players absorb the densification layer.

The most interesting development for a data center banker is that the tower REITs are pursuing sharply different strategies as the lines between network and compute blur. American Tower made the boldest move toward data centers, acquiring CoreSite for $10.1 billion in 2021 to build a "tower-plus-edge" platform that combines towers, interconnection, and edge data centers, on the thesis that cloud on-ramps and edge compute will increasingly sit alongside the network. It later sold a 29% stake in the CoreSite data center business to Stonepeak for $2.5 billion, recycling capital while keeping the strategic edge exposure.

Crown Castle went the opposite way. In a deal completed on May 1, 2026, it sold its entire fiber and small-cell business for $8.5 billion, with EQT taking the small-cell unit and Zayo acquiring the fiber, to become a pure-play domestic tower company. SBA, meanwhile, has explored a sale of its own as infrastructure consolidation accelerates. The strategic divergence is the story: one operator betting that towers and data centers converge, another stripping back to pure towers, and a third weighing an exit entirely.

For the deeper mechanics of the tower business specifically, the tower companies and infrastructure REITs article in the TMT guide goes further into the carrier relationships and the technology cycle. From the real estate side, the relevant point is that towers are a sibling asset class to data centers, sharing the REIT structure, the concentrated-tenant model, and exposure to the same digital-demand wave.

The tower REITs are best understood as the original digital-infrastructure asset class, with economics that prefigure the data center story: long leases, creditworthy but concentrated tenants, AFFO-based valuation, and powerful operating leverage from adding tenants to a fixed cost base. The convergence with data centers, through American Tower's edge strategy and the broader push of compute toward the network edge, is why the two increasingly appear in the same coverage scope and the same conversations.

Towers earn their returns through the tenancy ratio, where each added carrier is nearly pure profit; the Big Three dominate a concentrated market on both the supply and demand sides; and the sector is splitting between operators converging toward data centers and those retreating to pure towers. A candidate who can connect the tower model to the data center model, same structure, same concentration, same demand driver, has shown the kind of cross-asset fluency that real estate coverage of digital infrastructure increasingly requires.