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 oil and natural gas producer ATP Oil & Gas (Nasdaq: ATPG) fell as much as 17.2% this morning on a series of big-volume spikes before climbing back to a smaller 4% drop in lighter afternoon trading.

So what: ATP's move was an amplified version of the charts for rivals such as McMoran Exploration (NYSE: MMR), Forest Oil (NYSE: FST), and Callon Petroleum (NYSE: CPE), all of which fell more than 8% before bouncing back to total swoons in the 3% range. None of these tickers are tied to any specific bad news today -- it's just an (over-)reaction to the market's panicky mood today.

Now what: It bears mention that all of these suffering stocks carry four- or five-star ratings in our CAPS system out of five possible, all with approval ratios north of 95%. Unless every oil well runs permanently dry next week, I think we're looking at a whole bunch of prime buying opportunities on these kinds of unmotivated drops. I've never owned an oil stock in my life, but this is starting to feel like a good time to get started.

Interested in more info on the small-cap petroleum stocks we've mentioned? The Fool can help: