There are always red arrows pointing down.

Investors saw plenty of that last week, but there were some stocks that fell harder than others. Crummy earnings, bad corporate decisions, and investor apathy will find some companies falling out of favor every single week.

Let's take a closer look at five of this past week's biggest sinkers.

Company

2/25/11

Weekly Loss

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NutriSystem (Nasdaq: NTRI)

$13.89

(37%)

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Barnes & Noble (NYSE: BKS)

$13.71

(26%)

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Golden Star Resources (AMEX: GSS)

$3.12

(23%)

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Protalix Bio Therapuetics (AMEX: PLX)

$7.63

(21%)

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Gerova Financial (NYSE: GFC)

$5.28

(20%)

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Source: Barron's.

NutriSystem was the market's biggest loser, shedding some serious weight after the dieting specialist posted uninspiring results. Analyst downgrades followed its 17% decline in revenue. It's not a consumer trend against managed weight loss plans. Weight Watchers (NYSE: WTW) was one of the prior week's biggest winners after it posted a surprising surge in global paid weeks.

Investors threw the book at Barnes & Noble after the bookseller missed Wall Street's profit targets for the holiday quarter. This wasn't really a surprise. However, the superstore chain's decision to nix its dividend to devote more of its resources to its questionable digital strategy is what really scared shareholders away.

Golden Star is a Denver-based gold explorer with chunky gold mine interests in Ghana. Its latest quarter was a downer. Posting a loss as the shiny metal's prices are spiking is problematic, but the real concern here is the lack of gold production. Lower recoveries led to a 28% dip in gold sold during the quarter.

It was down with Uplyso for Protalix. The Gaucher's disease drug that Protalix is developing with Pfizer (NYSE: PFE) didn't clear its latest clinical trial. The Food and Drug Administration wants more information before approving the treatment. Pfizer's stock barely budged on the news because it's a well-diversified pharmaceuticals giant. For an upstart biotech like Protalix, though, Uplyso's ultimate approval is what separates feast from famine.

Gerova Financial is still backpedaling. The Bermuda-based reinsurer lost more than half of its value the prior week as accusations of financial shenanigans grew louder. The New York Stock Exchange halted trading in the stock this past Wednesday, seeking clarity on the allegations.

It was a rough week for these five stocks. Let's see which ones bounce back this week.

Which of these five stocks do you think will bottomed out last week? Share your thoughts in the comment box below.