T-Mobile US shares plunged 8.38% during intraday trading on Thursday, making it one of the worst performers in the S&P 500 and Nasdaq 100. The sell-off came after the wireless carrier reported second-quarter financial results that, while beating profit expectations, fell short on the top line and showed a deceleration in key subscriber metrics.

The company posted adjusted earnings of $2.99 per share, significantly above the analyst consensus of $2.59. However, quarterly revenue came in at $22.79 billion, missing the expected $22.94 billion. This revenue shortfall was a primary trigger for the negative market reaction, as investors focused on the top-line miss as a potential signal of slowing growth momentum. Additionally, T-Mobile added 277,000 net postpaid accounts during the quarter, which, while above estimates, represented a 13% decline from the same period a year earlier. The company also issued third-quarter net postpaid account addition guidance of approximately 250,000, below some analyst projections, further dampening sentiment.

Several other factors contributed to the decline. The company is phasing out older wireless plans and migrating customers to newer, more expensive rate plans, a move expected to temporarily increase customer churn. Broader market conditions also weighed on the stock, with U.S. equity indexes falling amid resurgent oil prices and concerns over heavy AI spending following Big Tech earnings. Despite raising its full-year adjusted free cash flow guidance to between $18.4 billion and $18.8 billion, the combination of a revenue miss and near-term subscriber growth headwinds drove the sharp intraday drop.