Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shareholders of biotech firm Dendreon (Nasdaq: DNDN) took it on the chin yet again this morning, with the company down as much as 14% following good study results from a rival and the disclosure of an SEC investigation.

So what: In a mid-stage study, Johnson & Johnson's (NYSE: JNJ) prostate cancer treatment, Zytiga, was found to have completely eliminated cancer, when combined with other therapies, in a third of all patients. This is particularly bad news for Dendreon since Zytiga looks to be on the path to becoming a direct competitor to Dendreon's prostate cancer treatment, Provenge. Even worse, Zytiga's cost of $5,000 represents a remarkably cheaper alternative to Provenge's $93,000 cost. Zytiga was originally set up to compete against Medivation's (Nasdaq: MDVN) enzalutamide, but when the study was unblinded, the results weren't significant enough to support the notion that it performed better than Medivation's drug. It did, however, show strength in other stages of the diseases, hence Dendreon's new worry.

To add insult to injury, the Securities and Exchange Commission disclosed a formal investigation into the company, which the company believes is based on potentially misleading statements surrounding Provenge and the company's finances. Now that's what I call a daily double-whammy!

Now what: Since "duck and cover" isn't officially listed as an investment strategy, today's move lower could represent an interesting buying opportunity if you think Dendreon can persuade physicians to prescribe its treatment. Dendreon's drug launch has been less than comforting for investors, and sales are moving in the right direction -- just not nearly as quickly as everyone had hoped. I remain optimistic that it will turn things around, but I must admit, my patience is waning.

Craving more input? Start by adding Dendreon to your free and personalized Watchlist so you can keep up on the latest news with the company.