Stupidity is contagious. It gets us all from time to time. Even respectable companies can catch it. As I do every week, let's take a look at five dumb financial events this week that may make your head spin.

1. There's a gap for that
Luke Wilson? You're wanted back on the set for some more Verizon-bashing ads.

AT&T (NYSE:T) has some more explaining to do, after temporarily suspending iPhone sales to potential online buyers who entered Manhattan ZIP codes during the Christmas holiday weekend. Sales resumed on Monday, but this can't sit well with Apple (NASDAQ:AAPL).

AT&T's connectivity issues, particularly within New York City and San Francisco, have made it a laughingstock among wireless carriers. Verizon's "There's a Map for That" campaign hit a nerve, but even AT&T's rebuttals, in which the company touts that AT&T covers 97% of the nation's population, are weak. Seriously. How can any phone company brag about reaching only 32 of every 33 people in the United States? That 33rd person may be important, you know. I can picture the Verizon attack ad perfectly.

Slowing the sale of iPhones into New York City may ease congestion on AT&T's overburdened data network in Gotham, but you can bet that Apple is fuming over the phone sales that got away.

2. It's a clearance Zale        
Shares of Zale (NYSE:ZLC) took a hit on Monday, after Citigroup (NYSE:C) announced that it wouldn't renew its branded credit card contract with the high-end jeweler when it comes up in March 2011.

This is ridiculous on many different levels.

  • The Citibank-backed Zales Diamond Card is good only at Zales. Are there really that many perpetual jewelry shoppers?
  • The allure of the store-tethered plastic is the deferred credit option, but that's a recipe for disaster. Heavy spenders with the means to pay off their bills monthly would be better off with their own reward-point cards. Who does that leave swiping the Zales-branded card?
  • Finally, not to be cruel, but is Zale even going to be around in its present form in 16 months? The retailer denied news reports that it has hired a restructuring consultant, but it did admit the need to evaluate its business in light of rising debt and falling comps.

3. Pfizer pfails
Pfizer's (NYSE:PFE) once-promising cancer treatment may be a dud after all. The pharmaceuticals giant is calling off the phase 3 trial of figitumumab as a life extender for lung cancer patients, and not just because its name is more than a mouthful.

"The company had already stopped enrollment in the trial after the monitoring board saw an increase in side effects, including death, in the patients taking figitumumab," writes our own Brian Orelli. Yep, it doesn't get much worse than death as far as side effects go.

The treatment isn't necessarily toast, though. Pfizer may very well make it work to treat either other forms of cancer or in combination with a different set of drugs. Either way, making it all the way to the third phase of clinical trials and then flopping isn't pretty.

4. Coffee, tea, or flee
Airline stocks got hammered earlier this week, after an averted Christmas Day terrorist incident forced carriers to adopt stricter in-flight standards. Banning the use of electronics on inbound international flights and subjecting passengers to lengthier security checks may be just knee-jerk reactions, but they're only going to turn more potential passengers off from traveling.

The legacy carriers can't afford the defections. Jet fuel prices soared in 2009, and airlines can't fill empty seats at high price points if demand isn't there. You probably didn't need another reason to avoid the airline industry, but you've got it. This may work out well for companies including OSI Systems (NASDAQ:OSIS) that make gear to improve airport security screenings, but not for the legacy carriers.

5. Double-dipping at Broadcom
The option-backdating saga is over at Broadcom (NASDAQ:BRCM). The company agreed to settle a class-action lawsuit for $160 million in cash. Affected shareholders were on the receiving end of the payouts, but investors still lost out. The stock took a 1.8% hit -- or roughly $280 million in market cap -- on the Monday news.

Poor Broadcom investors. First, they suffered when Broadcom first discovered the backdating, which cherry-picked stock lows retroactively as strike prices on option grants. That led to a $2.2 billion charge in early 2007. Now, they're getting dinged by a share price hit that is greater than the reward.

Let's beat the Dumb Drum:

Apple and AT&T are Motley Fool Stock Advisor recommendations. Pfizer is a Motley Fool Inside Value choice. Try any of our Foolish newsletter services, free for 30 days. That certainly wouldn't be a dumb move.

Longtime Fool contributor Rick Munarriz is a fan of dumb and smart business moves alike, since investors can learn plenty from both. He owns no shares in any of the stocks in this story and is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.