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 producer TransAtlantic Petroleum (AMEX: TAT) fell as much as 12% today after the company's COO announced he would step down.

So what: Gary Mize was the company's president and COO, and a reason for his departure wasn't given. He will be replaced by Mustafa Yavuz, who came onboard when the company acquired Thrace Basin Natural Gas. The company also said production to end 2011 was 5,651 net barrels of oil equivalent.

Now what: A management shakeup often scares investors a bit, so the reaction early in trading was natural. The company has struggled to get to profitability recently, and maybe it was a good time for a change with the stock trading this low. I don't see this as a buy sign, but keep an eye on results in the future to see if management can turn operations in a positive direction.

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