The Dow Jones Industrial Average (INDEX: ^DJI) slipped only 0.47% this week, but several of its components did far worse:

Company

Weekly Price Change

Travelers (NYSE: TRV) (5.7%)
Verizon (NYSE: VZ) (4.5%)
AT&T (NYSE: T) (4.4%)

Why, you ask, did shares of these three companies flame out?

Travelers is trying to recover from a year of catastrophe losses, but it fell victim to a tough underwriting and investing market in the fourth quarter. The insurer narrowly missed analyst expectations, which predicted a 31% decline in net income.

Before this week, Verizon shareholders had been licking their chops, wondering how strong iPhone sales growth would be. The quarter's total came in at 4.2 million, more than double last quarter's. But it turns out the phones aren't as profitable for Verizon as people thought they would be, on account of the heavy subsidies Verizon needs to pay Apple (Nasdaq: AAPL). While Verizon's margins shrunk, booming margins were a major contributor to Apple's blowout $13 billion quarterly profits.

Verizon's CFO tried to reassure investors, hinting that margins could improve in 2012. But longtime iPhone carrier AT&T's margins have been steadily declining for years before falling apart this fourth quarter.

The iPhone is becoming so popular that carriers are increasingly looking like commodity suppliers for Apple to squeeze at will. As one analyst put it, the iPhone has "really been a wealth transfer from AT&T shareholders to Apple shareholders." And with AT&T, Verizon, and Sprint Nextel now lining up to offer the iPhone, I don't see how that equation fundamentally changes. If you're looking for some "hidden" stocks ideas to profit off the biggest trend in tech, check out The Motley Fool's "3 Hidden Winners of the iPhone, iPad, and Android Revolution." I invite you to download this special report for free.

Ilan Moscovitz and The Motley Fool own shares of Apple. Motley Fool newsletter services have recommended buying shares of and creating a bull call spread position in Apple. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.