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. Two Rens don't make a right
The already rocky relationship between China's Renren (NYSE: RENN) and investors became even more strained after the social networking site delivered a ho-hum quarterly report.

Losses continued, and revenue climbed 47% to $20.6 million. This might be acceptable for an unknown upstart, but not for a company valued in the billions.

Renren went public at $14 last month, rising as high as $24 on its first day of trading. The stock has gone on to give up half of its IPO price, or more than two-thirds of last month's high.

Revenue grew 64% last year, so the seemingly heady 47% top-line spurt this time around is actually a serious case of deceleration.

2. Nokia's orphan
Nokia
(NYSE: NOK) unveiled its N9 handset during this week's Nokia Connection strategy day in Singapore.

There will often be debate on the potential success or failure of new smartphones, but you won't find too many N9 cheerleaders. The N9, after all, will be the first -- and likely only -- phone using the once-ballyhooed MeeGo operating system.

Nokia is accepting billions to champion Microsoft's (Nasdaq: MSFT) Windows Phone 7, and MeeGo is an unfortunate casualty.

The folks investing in an N9 phone may very well be the same ones who paid up for Microsoft's short-lived Kin.

3. Earnings are for closers
FSI International
(Nasdaq: FSII) added insult to injury by putting out disappointing guidance for the current quarter after coming up short on the top line in its fiscal third quarter.

The maker of capital equipment for the microelectronics industry sees itself earning $0.06 to $0.09 a share for the current quarter on $25 million to $30 million in revenue. The problem there is that the pros were targeting a profit of $0.12 a share on more than $32 million in revenue.

A miss and a diss is no way to end up with a kiss.

4. Achillion heel
Sometimes Mr. Market is the dummy.

Upstart biotech Achillion Pharmaceuticals (Nasdaq: ACHN) was one of Wednesday's biggest winners, soaring 21% to $7.26 after completing a secondary offering at $5.90 a share.

I get the sigh of relief. Achillion needed the money to move its potential blockbuster treatments for chronic hepatitis C along. The company was also able to float more shares than it had originally announced, going from 9 million on Monday to 9.6 million on Wednesday.

However, the cold hard truth is that this dilution took place at $5.90, a discount to where the shares were trading even before Wednesday's pop.

We're a few regulator nods away from the point where we would be quibbling between $5.90 and $7.26 price points, but it just feels as if Wednesday's euphoric reaction was way overdone.

5. A tree house falls in the woods
TreeHouse Foods
(NYSE: THS) is serving up indigestion after hosing down its near-term prospects.

The maker of private-label food products is blaming the spike in commodity costs for crimping margins during the current quarter and for the entire year. It's naturally harder for a private label specialist to adjust prices than it is for premium brands, but we can't cut TreeHouse Foods a break here.

A miss is a miss.

Perhaps more importantly, this is the kind of news that may lead shareholders to wonder if consumers are bypassing store brands in favor of the name brands that they traded down from when the economy was falling apart.

Which of these five moves do you think is the dumbest? Share your thoughts in the comment box below.

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Longtime Fool contributor Rick Munarriz is a fan of dumb and smart business moves. Investors can learn plenty from both. He does not own shares in any of the stocks in this story. Rick 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.