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⚠ When the Licences Are Worth LessLow threat

T-Mobile US (TMUS) — threat to the moat

T-Mobile carries $98 billion of spectrum at cost; past goodwill impairments of $10,984 million show what a write-down looks like.

The $98 billion of spectrum on T-Mobile's balance sheet is a historical cost, not a market price1. As long as nobody tests it, it never changes. Goodwill shows what testing can do: T-Mobile's goodwill note carries accumulated impairment losses of $10,984 million from earlier years2.

T-Mobile balance sheet items, end-2025 ($M)98,032Spectrum licences13,678Goodwill10,984Accumulated goodwill impairmentT-Mobile US Form 10-K FY2025, Note 7
The licences dwarf everything that has been written down.

The market occasionally prices spectrum for it. Auction 113 cleared 102 AWS-3 licences for $278 million3, and the 3.45 GHz sale fetched $2.0 billion4. If buyers of spectrum keep paying less for capacity than the merger price implied, the book value stops describing what the licences would fetch.

Write-downs have come before, outside spectrum. In 2022 T-Mobile recorded a $477 million impairment on its wireline business5, which it then sold to Cogent for a total purchase price of $16. The 2025 billing-system impairment cost $208 million after tax7. Each was small against the company and large against the assets written down.

The test itself is light. For its spectrum impairment assessment T-Mobile says "we employed a qualitative approach" and found no events indicating the fair value had fallen below the carrying amount8. A qualitative test asks whether anything has changed, not what the licences would fetch; it will catch a shock, not a slow decline in what spectrum is worth.

An impairment would not cost cash, but it would tell owners what the Sprint premium was worth. A spectrum impairment charge in any 10-K, however small, would be the first sign; there has been none on the licences, while a $278 million impairment of a billing system was recorded in 20259.

References
  1. ReportedThe $98 billion of spectrum on T-Mobile's balance sheet is a historical cost, not a market price.
    T-Mobile US, Inc. Form 10-K for fiscal 2025 (year ended 31 December 2025) - spectrum: holdings by band, licence transactions and the spectrum roll-forward. — FY2025 · publ. 11 February 2026 · source ↗
  2. ReportedGoodwill shows what testing can do: T-Mobile's goodwill note carries accumulated impairment losses of $10,984 million from earlier years.
    T-Mobile US, Inc. Form 10-K for fiscal 2025 (year ended 31 December 2025) - consolidated financial statements, segment expense table, cash flow and capital returns. — FY2025 · publ. 11 February 2026 · source ↗
  3. ReportedAuction 113 cleared 102 AWS-3 licences for $278 million, and the 3.45 GHz sale fetched $2.0 billion.
    T-Mobile US, Inc. Form 10-Q for the quarter ended 30 June 2026 - Deutsche Telekom ownership and voting control at 17 July 2026, the i3 Broadband and GoNetspeed/Greenlight fiber joint ventures, Auction 113, the Grain spectrum sale, litigation and cybersecurity risk. — Q2 2026 · publ. 23 July 2026 · source ↗
  4. ReportedAuction 113 cleared 102 AWS-3 licences for $278 million, and the 3.45 GHz sale fetched $2.0 billion.
    T-Mobile US, Inc. Form 10-K for fiscal 2025 (year ended 31 December 2025) - spectrum: holdings by band, licence transactions and the spectrum roll-forward. — FY2025 · publ. 11 February 2026 · source ↗
  5. ReportedIn 2022 T-Mobile recorded a $477 million impairment on its wireline business, which it then sold to Cogent for a total purchase price of $1.
    T-Mobile US, Inc. Form 10-K for fiscal 2022 - the 2020-2022 revenue lines with wholesale and other service revenues combined, Sprint merger costs of $4,969 million in 2022, the wireline sale to Cogent for $1, the 2021 cyberattack settlement and 2023 synergy guidance. — FY2022 · publ. February 2023 · source ↗
  6. ReportedIn 2022 T-Mobile recorded a $477 million impairment on its wireline business, which it then sold to Cogent for a total purchase price of $1.
    T-Mobile US, Inc. Form 10-K for fiscal 2022 - the 2020-2022 revenue lines with wholesale and other service revenues combined, Sprint merger costs of $4,969 million in 2022, the wireline sale to Cogent for $1, the 2021 cyberattack settlement and 2023 synergy guidance. — FY2022 · publ. February 2023 · source ↗
  7. ReportedThe 2025 billing-system impairment cost $208 million after tax.
    T-Mobile US fourth-quarter and full-year 2025 results release, Form 8-K exhibit 99.1 - broadband customers, shareholder returns of $14.0 billion in 2025 and the network-award record. — FY2025 · publ. 11 February 2026 · source ↗
  8. ReportedFor its spectrum impairment assessment T-Mobile says "we employed a qualitative approach" and found no events indicating the fair value had fallen below the carrying amount.
    T-Mobile US, Inc. Form 10-K for fiscal 2025 (year ended 31 December 2025) - spectrum: holdings by band, licence transactions and the spectrum roll-forward. — FY2025 · publ. 11 February 2026 · source ↗
  9. ReportedA spectrum impairment charge in any 10-K, however small, would be the first sign; there has been none on the licences, while a $278 million impairment of a billing system was recorded in 2025.
    T-Mobile US, Inc. Form 10-K for fiscal 2025 (year ended 31 December 2025) - spectrum: holdings by band, licence transactions and the spectrum roll-forward. — FY2025 · publ. 11 February 2026 · source ↗
Sources
Generated October 6, 2026