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. Palm someday
Sprint Nextel (NYSE:S) needs to make up its mind. The company's ticker symbol may as well be short for the split-personality flick Sybil.

The wireless giant turned heads on Tuesday, when it offered $100 in service credit to customers of rival carriers interested in porting over their service to Sprint through a new Palm (NASDAQ:PALM) Pre. Sprint was selling the smartphone for a subsidized $199 with a two-year contract at the time, so the deal effectively shaved the price to an attractive $99.

The deal lasted for a few hours. Sprint then pulled the offer and explained that it was put into the system by error.

The next morning, Sprint cut the price of the Pre for all users to $149.

Why not go for $99 and truly take on the entry-level $99 iPhone 3G? Why go through the whole rigmarole with the bogus "port in" tease? Sprint has other phones to sell, but this back-and-forth reflects poorly on Palm, which is just an innocent bystander.

2. Mum's the word at Amazon     
I guess I'm not alone in calling out Amazon.com (NASDAQ:AMZN) and its sealed-lip ways when it comes to its breakthrough Kindle e-book reader. Apple's (NASDAQ:AAPL) Steve Jobs was asked about the Kindle on Wednesday.

"You notice Amazon never says how much they sell," Jobs told The New York Times. "Usually if they sell a lot of something, you want to tell everybody."

I guess the same goes for Apple, which is quick to update investors on its tally of iPods, iPhones, and MacBooks sold during any given quarter but isn't as proud of its Apple TV metrics.

Jobs is right, though. Amazon released the Kindle nearly two years ago, and we still don't have any idea if it's a hit or not. Even if Amazon is staying quiet to keep rivals away, it's not fair to buyers of the device or to the publishers being wooed to sell e-books.

3. Yahoo!'s your baddie
Tsk, tsk, Yahoo! (NASDAQ:YHOO). The U.K. newspaper The Guardian is calling out CEO Carol Bartz for selling roughly $2 million worth of Yahoo! shares, even though she's been at the helm for less than a year. Nice show of confidence, there, Bartz.

However, I'm going to send some raspberries The Guardian's way, too. This is old news. Bartz sold her shares in March and June. It's only news if she unloads stock this month in a quarterly rite.

It's certainly not cool to see Bartz sending an unappetizing message, but she's also a bit flunky when it comes to the timing of her insider selling. She sold her first batch of shares in March at a price of $12.81 a share. She could have made quite a bit more if she had held on to sell it with the June shares she unloaded at $15.66 a share.

So we have three Dumb Trophies to hand out here. Bartz gets one for rookie selling in a turnaround situation. She gets a twofer because of lousy timing. The third trophy goes to Guardian for reporting old news.

OK, I'll take one of those trophies, too. If I'm going to call out a company for reporting old news, I'm sort of doing the same thing.

4. Rough landing
AeroVironment (NASDAQ:AVAV) has landed. The maker of unmanned aerial vehicles -- the gee-whiz gadgetry that helps our country's military check out what the other guys are doing without risking soldier casualties -- is mortal. AeroVironment posted its first quarterly loss as a public company.

So far, so bad. Every company is entitled to the occasional miss. Things get interesting here, though. AeroVironment is soothing investor concerns by assuring them that Pentagon orders that didn't materialize during the quarter will still happen later this year.

Try telling that to Janney Montgomery Scott analyst John M.A. Roy. He downgraded the stock by lowering AeroVironment's projected earnings for both 2009 and 2010.

Somebody -- or some company -- is very wrong here. Let's hope AeroVironment is using some of its unmanned flying machines to snoop on the future.

5. You never give me your money
The smacked-around video game industry turned to Viacom's (NYSE:VIA) The Beatles: Rock Band for salvation on Tuesday. The eagerly anticipated music game allows players to jam -- and harmonize -- along to tunes from the world's most influential rock band.

The problem is that Viacom's bundle -- featuring controllers in the form of Ringo Starr's drum kit and Paul McCartney's bass -- will set gamers back $250. If they want the limited-edition John Lennon and George Harrison guitar controllers, they run $99 apiece.

Most gamers will simply buy the $60 game and use their old guitar controllers, but Viacom is just outright insensitive to price a full band set for $450. Yes, I know it's the Beatles. However, when you price a game for more than any of the three consoles it could play on, you're going to be seen as greedy at an inopportune time.

Let's beat the Dumb Drum:

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Sprint Nextel is a Motley Fool Inside Value recommendation. AeroVironment is a Motley Fool Rule Breakers selection. Apple and Amazon.com are Motley Fool Stock Advisor recommendations. 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. Investors can learn plenty from both. Howns 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.