AMERICAN TOWER CORP /MA/ (AMT) stock intrinsic value fair value estimate & owner earnings analysis

American Tower owns and operates wireless communications towers and, since its 2021 acquisition of CoreSite, a network of interconnected data centers. Over the past several years the company has substantially reshaped its footprint: it sold its Mexico fiber and Poland businesses in 2023, its Australia, India and New Zealand towers businesses in 2024 (the India exit was the largest, closing in September 2024 for roughly $2.5 billion), and its South African fiber business in 2025. What remains is a business concentrated in U.S. towers, a smaller set of stable international tower markets, and the CoreSite data center platform. The core of a tower business is straightforward: towers generate rent from wireless carriers and other tenants, contracts include automatic price escalators, and once a tower is built, adding a new tenant costs relatively little. That makes the underlying cash generation durable, but it also means the company depends heavily on just three national wireless carriers as its major U.S. tenants, and it operates with a substantial amount of debt that must be continually refinanced -- both of which we treat as the key risks. Cash generated by the business, after removing the swings from working-capital timing, stock compensation, and the portion of capital spending that is for maintaining rather than growing the network, grew steadily from a little under $5 per share in 2016 to roughly $8 per share in 2024, before printing essentially flat in 2025 -- the final year of the divestiture program. More recent results (the first half of 2026) show revenue and cash flow accelerating again, which we take as evidence that operations have returned to a clean run rate now that the divestitures are complete, and it supports a modest step-up in near-term growth from the roughly flat trailing pace. We valued the company on that normalized cash-generation level of roughly $8 per share, discounted over ten years, plus a view of what the business is likely to sustain beyond that. In our base case, growth cools gradually from about 5% in year one to roughly 3.5% by year ten, reflecting continued 5G-driven tenant additions and CoreSite leasing, tempered by a maturing tower market. Because towers carry very long economic lives and much of the ongoing cost of maintaining them is already captured in our maintenance-spending estimate, we treated the years beyond the ten-year forecast as an extended, slow-growing (roughly 1% a year) stream rather than a hard cutoff -- essentially crediting the business with continuing to collect escalator-driven rent from a well-established tenant base. That long tail makes up a large share of the total value here (roughly two-thirds), which is typical for infrastructure businesses with contracted, multi-decade tenant relationships, but it does mean the valuation leans heavily on carrier tenancy persisting largely as it exists today. Our bear case assumes one of the three major U.S. carriers meaningfully consolidates or reduces its site footprint, cutting a chunk of rental revenue in the first year, after which growth stalls entirely as continued high debt-refinancing costs offset the built-in rent escalators; we do not assume any recovery, and value runs through to a modestly shrinking perpetuity. Our bull case assumes CoreSite's data-center leasing accelerates meaningfully on rising interconnection demand and U.S. tower leasing activity stays elevated for longer than the base case assumes, sustaining high-single-digit growth for several years before settling to a still-respectable pace. On this basis, we estimate the shares are worth roughly $116 in the bear case, $199 in our base case, and $240 in the bull case. Given the gap between the bear and base cases, the margin-of-safety price is meaningfully below our base-case estimate -- around $145 -- reflecting the leverage and tenant-concentration risks described above. One accounting note: a large share of annual depreciation and amortization comes from write-downs of acquired intangibles (from CoreSite and from towers acquired over the years) and, in 2023, a roughly $1.2 billion non-cash loss on the sale of the India business. Because these are non-cash and don't recur at that scale, we added them back in full when computing cash generation -- but we also capped the long-term growth rate at a modest level specifically so the valuation doesn't implicitly treat the earning power created by past acquisitions as permanent, free of any decay. We were not able to fully reconcile 2022 revenue on a like-for-like basis against the operations since divested, so that year's growth comparison carries some noise; we've noted this in how the underlying cash-flow history was normalized.