MPLX to buy MarkWest Energy in ~$20B deal

• MPLX agrees to acquire MarkWest Energy Partners (NYSE:MWE) in a cash and stock deal valued at ~$20B, including ~$4.2B in debt.
• MWE unitholders will get 1.09 common units of MPLX and $3.37 in cash for every unit held, which works out to $78.64/unit, a 32% premium to MWE's Friday closing price.
• The deal would create the fourth-largest MLP, with a $21B market cap.