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.


Oct. 4

Weekly Loss

Angie's List (NASDAQ:ANGI)






Arena Pharmaceuticals (NASDAQ:ARNA)



Diamond Foods (NASDAQ:DMND)



J.C. Penney (NYSE:JCP)



Source: Barron's.

Let's start with Angie's List, the premium online website operator that offers vetted service reviews. The company confirmed last week that it's testing a new $10 annual membership in some key markets. That's a 75% discount to its current $40 rate. 

The Wall Street Journal went on to report that the $10 offers reverted back to $40, but the damage has been done. Fears that Angie's List memberships are sliding -- forcing Angie's List to this dramatic test -- are scaring away investors.  

GTx slipped after informing its workforce on Tuesday that 60% of them will be let go. The biotech was pounded this summer after a failed late-stage drug trial for GTX-024, GTx's lead candidate that aimed to prevent the wasting away of muscle mass for lung cancer patients. GTx is still gunning for approval overseas, but it will have to do so with 53 fewer non-executive employees.

Arena Pharmaceuticals lost some weight after a pair of unflattering analyst moves. First it was Credit Suisse slashing its price target on the obesity drug market from $5 to $4. Then Cowen initiated coverage with a ho-hum "market perform" rating. Credit Suisse analyst Lee Kalowski sees soft sales for Arena's Belviq after analyzing three months of prescription data.

Diamond Foods more than reversed the prior week's 10% gain after posting disappointing quarterly results. Earnings did clock in ahead of expectations, but it was the weak guidance that led investors to cash out of the salty-snacks giant. 

It certainly seemed as if the company behind Kettle Brand potato chips, Emerald nuts, and Pop Secret microwaveable popcorn was positioned well after an upgrade from BB&T Capital Markets just days before the earnings release. It didn't pan out that way.

Finally we have J.C. Penney falling to levels last seen in 1982, as the department-store chain received yet another analyst downgrade. This time it was Maxim Group reacting to the retailer's slippery financials. Raising funds in a desperate stock offering also didn't impress Fitch, which lowered its credit rating on J.C. Penney.

Longtime Fool contributor Rick Munarriz and The Motley Fool have no position in any of the stocks mentioned. 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.