The Hidden Cost of AT&T Stock’s Success

The company is winning subscribers with its fiber and wireless bundles, but the strategy may be quietly eroding the profitability of its most important asset.

For anyone holding AT&T (T) stock, the recent results present a puzzle. The company is executing its strategy, adding over 1 million new high-value subscribers in the last quarter alone. Yet the stock has underperformed the market, down 9.0% over the past year while the S&P 500 is up 17.5%.

The market's hesitation points to a central risk that lies not in some external threat but within the company's very success. AT&T is growing, but the way it's achieving that growth may be creating a long-term problem for its most critical investment: the fiber network.

The Price of Winning Fiber Customers

AT&T's core strategy is "convergence," bundling its fiber internet and postpaid wireless services to create stickier, more valuable customers. It's working to attract users; 43% of its advanced home internet customers now also have a postpaid wireless account. The problem is the price of that success.

Management acknowledged that Fiber ARPU, or the average revenue per user, declined 1.3% from a year ago. While this was partly due to acquiring lower-priced customers from Lumen, executives noted that even excluding that deal, Fiber ARPU was only "approximately flat year-over-year." The CFO was direct about the trade-off, stating that the focus on converged customers who "enjoy discounted pricing" will "likely put some pressure on Fiber ARPU" in the near term. This is the risk in a nutshell: to win bundled subscribers, AT&T is sacrificing per-unit pricing on its flagship fiber product. If the main engine of future growth generates flat or declining revenue per customer, it challenges the economic returns on the billions being invested in network expansion.

Are Margins As Good As They're Going to Get?

This pressure on pricing power arrives at a moment when AT&T's profitability is at a peak. The company's net margin of 16.9% is well above its 3-year average of 10.8%, and its operating margin sits at the high end of its multi-year range. Management recently celebrated achieving its "highest consolidated adjusted EBITDA margin" in years.

While strong performance is welcome, peak margins are inherently vulnerable. They have more room to fall than to rise, and the squeeze on Fiber ARPU is a direct threat. If AT&T has to perpetually discount its best product to drive subscriber growth, especially as competitors like Starlink create more background noise, these historically high margins could begin to normalize downward. A reversion toward the average would directly impact the free cash flow that supports the company's dividend and its newly increased plan for approximately $10 billion in share repurchases this year.

The market already seems skeptical, assigning the stock a low P/E multiple. The core question for investors isn't whether AT&T can add customers, but whether the profit from each of those customers is sustainable. The clearest signal will be whether that flat-lining Fiber ARPU begins to bend back up, or continues to slide.

Where Else Is This Kind Of Risk Hiding?

A threat like this is a reminder that every stock you own carries risk you cannot always see coming, and the options market puts a number on exactly that uncertainty: the expected move it prices in for the year ahead. Our Expected Move screen shows which S&P 500 names carry the widest priced-in swings, so you can see whether the rest of your portfolio is sitting on risk you have not accounted for. And if you would rather not carry this one name's risk alone, a communication services ETF like XLC spreads it across the whole group.

How Do You Keep One Bad Surprise From Sinking You?

The risks worth worrying about are often the ones you cannot see coming, and no amount of homework on a single stock fully removes them. The reliable protection is structural: hold enough quality names, sized with discipline, that any one of them turning out badly is a dent, not a real setback. That is how careful investors stay in the game through the surprises.

It is exactly what the Trefis High Quality (HQ) Portfolio does for you, weighing the full picture of quality across thousands of names, holding the 30 strongest, and rebalancing them with rules. It has a track record of outpacing a benchmark that combines the three major indices - the S&P 500, S&P Mid-cap, and Russell 2000.