The week following Thanksgiving and Black Friday proved to be a bit rough for a few health-care stocks. There weren't many big drops, but we always have a few in the volatile world of biotech. Here are three of the most horrendous health-care stocks this week.

Super bad
Supernus Pharmaceuticals
(NASDAQ:SUPN) shares plunged nearly 32% for the week. The stock collapse followed an announcement on Thursday about a secondary offering of 6 million shares expected to net $51.5 million.

The additional 6 million shares represent almost 25% of the current total shares outstanding. With the stock falling several points more than this, did the market overreact to the prospect of share dilution? Nope.

Supernus priced the offering at $8 per share, but the stock's price in the days before the announcement hovered between $11 and $12 per share. It's no wonder shares plummeted.

A need for more cash to commercialize the company's two epilepsy drugs, Oxtellar XR and Trokendi XR, spurred the secondary offering. At the end of the third quarter, Supernus only had enough cash to take the company through second quarter of 2013. 

High-tech lows
Hi-Tech Pharmacal
(NASDAQ:HITK) stock sank  almost 11% this week. If you looked only at the company's news releases, you might scratch your head in wonder.

Hi-Tech announced a special one-time $1.50 dividend earlier today. It joins a number of other companies paying special dividends to help investors avoid a possible increase in taxes at the beginning of 2013.

The drop-off in the stock price began on Thursday. A short-seller published an article predicting that shares were likely to plunge due to poor earnings results to be announced in December and investigations relating to allegations of fraud. Another blow came from the analyst community as Standpoint Research downgraded Hi-Tech from buy to hold.

Shareholders likely were pleased with the special dividend. Fear, uncertainty, and doubt are difficult factors to overcome, though, whether justified or not.

Spinal tap
Rounding out this week's horrendous health-care performers is Globus Medical (NYSE:GMED). Shares for the spinal implant maker fell nearly 10% for the week.

Nothing unusual jumps out as the cause for the week's drop. The stock has been trading in a range after a sharp fall after Globus announced its quarterly results on Nov. 1. Earnings were slightly lower than the same quarter in 2011 because of the company's investments in a new interventional pain-management division.

Globus went public last August with an initial share price of $13.50. The stock shot up after the IPO, reaching a high point of nearly $20 in early October. However, it has drifted downward since then and now trades below the IPO price.

Coming close
Exelixis
(NASDAQ:EXEL) came close to making the horrendous list this week. Shares dropped nearly 8% for the week even though the FDA approved its cancer drug Cometriq.Others also came close but managed to stay off the list of some of the worst performers.

Overall, the past week had fewer big losers than average. As 2012 draws to a close, this trend could continue, with a lower number of companies reporting quarterly results and not as many big FDA announcements during the holidays. On the other hand, it's the stock market. And it's health care. Anything could happen.

Keith Speights has no positions in the stocks mentioned above. The Motley Fool owns shares of Exelixis. Motley Fool newsletter services recommend Exelixis. 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.