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Comcast and Charter: Rivals Who Sell It SpectrumNarrow moat

T-Mobile US (TMUS) — moat facet

Comcast competes with T-Mobile for wireless customers and is selling it 600 MHz spectrum for up to $3.4 billion.

The cable companies are a different kind of rival. T-Mobile's 10-K names Charter Communications, Comcast, Cox and Altice among its competitors, "many of which offer no-contract, postpaid and prepaid service plans"1. They sell mobile service to their broadband customers and compete with T-Mobile for the household bill.

Comcast 600 MHz spectrum purchase, total consideration ($M)1,200Minimum3,400MaximumT-Mobile US Form 10-K FY2025, spectrum transactions; mostly closing first half 2028
A rival selling it reach.

They are also suppliers. In September 2023 T-Mobile agreed to buy 600 MHz spectrum from Comcast, and after an amendment in January 2025 "the total cash consideration for the transaction is between $1.2 billion and $3.4 billion"2, with about $45 million of licences targeted for the first half of 2026 and the rest for the first half of 20283. A cable company competing for T-Mobile's customers is selling T-Mobile the low-band capacity that improves its reach.

The contest runs in both directions on broadband too. T-Mobile's home internet competes against "Cable, DSL and other Fiber broadband providers"4, and its 5G broadband base was 8,450 thousand at the end of 20255. The cable companies attack T-Mobile's phone business while T-Mobile attacks their internet business.

T-Mobile's release notes that "Comcast and Charter do not disclose postpaid phone net customer additions"6, so the size of their gains is not visible in comparable form.

The spectrum deal is the larger of the two relationships. The 10-K describes the Comcast licences as being acquired in exchange for cash under a License Purchase Agreement with Comcast and its affiliate Comcast OTR17. A rival that sells its unused spectrum to a competitor is judging that the cash is worth more than the capacity.

The relationship tilts T-Mobile's way while it is buying spectrum from cable and taking broadband customers from it. Spectrum purchases were $1,417 million in 20258; if T-Mobile's broadband growth stalled while cable's mobile offers kept growing, the trade would have turned.

Moat trajectory: Holding steady

Comcast 600 MHz purchase targeted for 2026 and 2028.

The number that tests this moat
Reported
Spectrum licences acquired, full year
$1,417M (FY2025)

How much capacity T-Mobile is buying, including from cable; a fall to near zero would mean it is no longer adding reach this way.

Source: T-Mobile US Form 10-K, FY2025 ↗
References
  1. ReportedT-Mobile's 10-K names Charter Communications, Comcast, Cox and Altice among its competitors, "many of which offer no-contract, postpaid and prepaid service plans".
    T-Mobile US, Inc. Form 10-K for fiscal 2025 (year ended 31 December 2025) - Item 1 business, the single Wireless segment, competition and the revenue lines with their drivers. — FY2025 · publ. 11 February 2026 · source ↗
  2. ReportedIn September 2023 T-Mobile agreed to buy 600 MHz spectrum from Comcast, and after an amendment in January 2025 "the total cash consideration for the transaction is between $1.2 billion and $3.4 billion", with about $45 million of licences targeted for the first half of 2026 and the rest for the first half of 2028.
    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 ↗
  3. ReportedIn September 2023 T-Mobile agreed to buy 600 MHz spectrum from Comcast, and after an amendment in January 2025 "the total cash consideration for the transaction is between $1.2 billion and $3.4 billion", with about $45 million of licences targeted for the first half of 2026 and the rest for the first half of 2028.
    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 ↗
  4. ReportedT-Mobile's home internet competes against "Cable, DSL and other Fiber broadband providers", and its 5G broadband base was 8,450 thousand at the end of 2025.
    T-Mobile US, Inc. Form 10-K for fiscal 2025 (year ended 31 December 2025) - acquisitions and joint ventures: UScellular, Metronet, Lumos, Ka'ena, Vistar and Blis. — FY2025 · publ. 11 February 2026 · source ↗
  5. ReportedT-Mobile's home internet competes against "Cable, DSL and other Fiber broadband providers", and its 5G broadband base was 8,450 thousand at the end of 2025.
    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 ↗
  6. ReportedT-Mobile's release notes that "Comcast and Charter do not disclose postpaid phone net customer additions", so the size of their gains is not visible in comparable form.
    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 ↗
  7. ReportedThe 10-K describes the Comcast licences as being acquired in exchange for cash under a License Purchase Agreement with Comcast and its affiliate Comcast OTR1.
    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 ↗
  8. ReportedSpectrum purchases were $1,417 million in 2025; if T-Mobile's broadband growth stalled while cable's mobile offers kept growing, the trade would have turned.
    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