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 Delek US Holdings (NYSE: DK) are on the mend today. The petroleum refiner was up a little more than 10% in early trading after reporting that normal operations had been restored at its Tyler, Texas, plant.

So what: The news comes on the heels of a report in the industry trade publication Offshore that Israeli parent company Delek Group is negotiating to acquire a majority stake in diversified real estate firm Cohen Development.

Now what: If there are synergies that offer a rationale for the deal, it's not obvious from Offshore's reporting, nor from the company's records in S&P Capital IQ. Yet synergy may not be the point. Delek Group has a diverse array of holdings, including stakes in El Al Airlines and Tower Semiconductor (Nasdaq: TSEM), among others. The implication? While Delek US investors have good reason to celebrate the end of trouble in Texas today, there's much more to the company behind this company. Have a different take? Please weigh in using the comments box below.

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