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: Shares of Star Scientific (Nasdaq: CIGX) fell 12% today, continuing a downward trend.

So what: Star Scientific, a tobacco curing technologist, started to fall off its high horse on Thursday after a long run-up, and it looks like the momentum continues today. There wasn't any significant news driving trading, but volume has again reached 6 million shares, which used to be off the charts for this extra-volatile stock.

Now what: Fellow Fool Brian Pacampara warned of buying into last week's sell-off, which looks like wise advice after another long fall today. There may be long-term drivers that will help the stock, but in the short term, this stock is a traders' dream, and investors should tread carefully. After all, the company doesn't have any significant revenue -- only the hope of products that show promise.

Interested in more info on Star Scientific? Add it to your watchlist.