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 Duncan Energy Partners (NYSE: DEP) soared more than 20% in intraday trading Wednesday after Enterprise Products (NYSE: EPD) offered to purchase the midstream energy firm for $42 per unit.

So what: The proposed deal, in which Enterprise would exchange 0.9545 of its units for each of Duncan's, values Duncan at about $2.4 billion and represents a 28% premium to yesterday's close. The move would allow Enterprise, which already owns 58% of Duncan, to own the company in full and significantly expand its pipeline services.   

Now what: The offer seems like an attractive one for Duncan. In addition to a juicy premium, the proposal gives Duncan shareholders a chance to, as Enterprise CEO Michael Creel puts it, "participate in the future growth of Enterprise, which has a backlog of pending capital projects and a more diverse existing asset base." For those who would rather cash out now, rivals El Paso (NYSE: EP) and ONEOK (NYSE: OKE), both of which sport clearly lower P/Es than Duncan, might be cheap ways to roll that natural gas bet over.

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