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 Forest Oil Corporation (NYSE: FST) fell 18% late today after its buyout came into question.

So what: Sabine Oil & Gas had previously announced a merger with Forest Oil that would have Sabine holders owning 73.5% of the new company and Forest Oil shareholders owning the remaining 26.5%. But Bloomberg is reporting that a $850 million loan was pulled by Sabine, money that was intended to repay Forest Oil borrowings when the merger went through.  

Now what: We need to keep in mind that this is an early report and nothing is final yet. But it's worth keeping an eye on because the proposed deal has held shares up recently. I don't think it's worth panicking yet, but if Sabine backs away from the buyout, shares could fall below $2, where they were before the merger was announced. For now, investors shouldn't change their investment thesis but evaluate Forest Oil as a standalone company, not just a buyout target.