There's never a shortage of losers in the stock market. Let's take a closer look at five of this past week's biggest sinkers.

Company

Oct. 25

Weekly Loss

NQ Mobile (NYSE:NQ)

$10.63

57%

Pacific Biosciences (NASDAQ:PACB)

$4.22

20%

Cree (NASDAQ:CREE)

$60.83

18%

Rentech Nitrogen (NYSE:RNF)

$23.56

18%

Akamai (NASDAQ:AKAM)

$45.88

12%

Source: Barron's.

Let's start with NQ Mobile. The provider of Internet services in China lost more than half of its value after a notable worrywart called the company a sham. Muddy Waters -- no stranger to calling out obscure Chinese growth stocks -- issued a report claiming that most of NQ's revenue was fictitious and calling into question the authenticity of its cash. NQ denied the allegations on Friday, but uncertainty will be hanging over the shares until it can prove that it's on the up and up. 

Pacific Biosciences of California had soared earlier this month after the maker of DNA sequencing systems sold worldwide rights to market human in vitro diagnostics products based on its Single Molecule Real-Time technology to a pharmaceuticals giant. This past week saw PacBio give a good chunk of its earlier gains away after revealing that it sold just six of its PacBio RS II DNA sequencing units in the third quarter, one fewer than it installed in the second quarter.

Cree got dim after offering up uninspiring guidance. The LED specialist sees a profit of $0.36 to $0.41 a share on $400 million to $420 million in revenue for the current quarter. Analysts were holding out for a larger profit, and Wall Street's top-line target of $414 million is just ahead of the midpoint of where Cree thinks it will land.  

Rentech Nitrogen Partners hit the dirt after the limited partnership that produces fertilizer announced a $0.27-per-unit distribution. That's a dramatic step down for the partnership that had paid out $0.85 a unit in its previous quarterly disbursement.

Finally we have Akamai proving mortal. The leading content-delivery network let the market down with its latest quarterly report. The quarter itself was solid -- beating expectations on both ends of the income statement -- but Akamai's guidance was a bit weak. The company explained that it's renegotiating terms with its biggest media customers, and in this cutthroat climate that usually translates into a sweeter deal for the customer.

Rick Munarriz has no position in any stocks mentioned. The Motley Fool recommends Pacific Biosciences of California. 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.