Most of us are rubberneckers. Some people can resist the urge to look at crashes along the way -- but I'm not one of them.

And I can't resist my rubbernecking tendencies with health-care stocks, either. Here are three of the most horrendous performers in the health-care investing world this week.

Thanks for nothing, FDA
ISIS Pharmaceuticals (IONS -1.44%) actually received some good news this week but still saw its stock perform horrendously. The Food and Drug Administration's metabolic drug committee narrowly gave the nod of approval to the company's cholesterol drug Kynamro, just as my fellow Fool David Williamson predicted. That paves the way for a final decision by the FDA, which usually goes with the recommendation of the committee but not always.

Shares of biotech companies usually go up following FDA committee approval. Not so for ISIS. Shares plunged more than 30% during the week. NPS Pharmaceuticals (NASDAQ: NPSP) also proved to be an exception this week. Despite gaining committee approval for Gattex, the stock sank.

The problem is that 3.1% of patients taking Kynamro during the clinical study developed tumors. Even if the FDA ultimately approves the drug, the safety issues raise concerns that Kynamro could only be allowed for very restricted usage. 

In need of alignment
Align Technologies (ALGN -1.04%), maker of the Invisalign braces system, saw shares plummet around 24% this week. The company announced preliminary third-quarter results that didn't cause any smiles.

The company stated that total revenue would increase by only 8.4% year-on-year, below expectations. Its announcement included fourth-quarter guidance that disappointed analysts. There is also the distinct possibility that Align will have a goodwill impairment charge in the next quarter related to its acquisition of Cadent.

There is some comforting news for Align investors who bought shares in 2011. Even with the sell-off this week, the stock is still up more than 70% over the past year. 

On a roll
Then there's MannKind (MNKD -0.24%). The company continues to be on a roll -- just not a good one. MannKind made the horrendous list last week also.

This long-suffering biotech's woes could easily belong in a country song. The verse about its latest problems would need to find a rhyming word for dilution. MannKind announced a new share offering this week that will dilute its stock further.

MannKind's shares dropped 18% on the week. The stock climbed by nearly 8% earlier in the week, but the share offering news wiped out those gains and piled on more losses as well.

Looking ahead
Looking ahead, we could see a near-miss for this week's list, like Dynavax Technologies (DVAX -2.19%), make its way to the hall of horrendousness. Dynavax dropped 16% this week. There wasn't any negative news, though. My hunch is we're just seeing some nervous jitters on the part of investors anxiously awaiting the FDA advisory committee meeting on Heplisav scheduled for November.

I don't see ISIS shares recovering quickly from the safety concerns raised by the FDA, so it might be another poor performer next week. I am hoping, though, that MannKind won't make our list next week. I like pulling for an underdog. 

The best long-term pick from our bad performers for the week is Align Technology. The third and fourth quarters might not look too great, but I have a positive view for the company's prospects over a longer horizon.

The health-care environment is such that horrendous stocks can quickly become humongous stocks. We might be compulsive rubberneckers, but it pays to keep our eyes on the road.