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 small-cap biotech Delcath Systems (Nasdaq: DCTH) popped more than 10% in intraday trading, as takeover rumors may have sparked investor excitement.

So what: The unconfirmed rumor has drug giant Bristol-Myers Squibb (NYSE: BMY) offering $15 for Delcath, representing a spectacular premium to its current price. While takeover talk is certainly cheap, it's widely known that Bristol, along with Onyx Pharmaceuticals (Nasdaq: ONXX), have been yearning to get into the liver cancer space.

Now what: Fools know never to jump into a stock on takeover speculation alone. But with Delcath recently validating positive trial results for its drug delivery system, as well as raising about $35 million in a secondary offering, the stock does sport some serious hidden potential. If Delcath gets its PHP system approved by mid-2011, like its CFO expects, today's speculation-fueled surge will likely be a drop in the bucket.

Update: On Friday, Oct. 8, Delcath shares moved an additional 14% in intraday trading on no new news.