T-Mobile Shares Slide on Renewed Competition Fears as Q2 Beat and Raised Guidance Fail to Reassure Investors

T-Mobile US shares closed at $176.26 on September 16, 2026, down 4.90% over the past month and roughly 28% over the past year, as renewed industry competition overshadowed an otherwise solid second-quarter earnings report. The stock underperformed its telecom peers on Thursday, September 17, with investors focused on aggressive promotional activity from AT&T and Verizon rather than the company's fundamental results.

T-Mobile's Q2 2026 results beat profit expectations but slightly missed revenue estimates. The company posted postpaid service revenue growth of 13% year-over-year, total service revenue growth of 9%, and core adjusted EBITDA growth of 12%, with a free cash flow margin of 25%. Postpaid net account additions reached 277,000, and average monthly postpaid revenue per account rose 2% year-over-year to $152.91, driven in part by a shift to premium plans, with roughly 60% of new customers adopting the top tier. The company raised its full-year adjusted free cash flow guidance to a range of $18.4 billion to $18.8 billion, up from a prior midpoint target of $18.0 billion to $18.7 billion, citing tax efficiencies and AI-driven working capital improvements. Full-year service revenue guidance stands at approximately $77 billion, representing 8% growth, while full-year core adjusted EBITDA guidance is set at $37.1 billion to $37.5 billion, up 10% at the midpoint.

Despite the strong operating metrics, analysts note that elevated carrier promotions are the central concern weighing on the stock. One analyst reaffirmed a Buy rating with a $230 price target as recently as early September, suggesting the market selloff may reflect sentiment rather than fundamentals. Morningstar analysis indicates that while competition is currently elevated, a rational pricing environment among T-Mobile, AT&T, and Verizon is expected to emerge over the longer term, supporting stable cash flow growth. A separate sector outlook identifies T-Mobile as leading the U.S. telecom peer group on valuation and free cash flow growth.

In a separate corporate development, former T-Mobile executive Mike Katz joined the board of MNTN, a connected TV performance advertising company, effective September 3, 2026. Katz was elected as a Class II director and will serve until the 2027 annual meeting of stockholders.