NEW YORK (TheStreet) -- Shares of Marathon Petroleum (MPC) - Get Marathon Petroleum Corporation Report jumped 7.8% after its master limited partnership, MPLX (MPLX) - Get MPLX LP Report, said it will buy natural gas processor Markwest Energy Partners (MWE) in a deal valued at roughly $15.8 billion.
MarkWest focuses on dividing natural gas into other types of fuels, like propane, while Marathon handles oil transportation through its pipelines, among other specialties. Shares of Marathon reached an all-time high for the year and was the best performing stock in the S&P 500.
But shares of the master limited partnership MPLX fell 14.5% on Monday and lost over 28% since the stock's high for the year back on March 2. The transaction values MPLX at $21 billion -- that's the fourth-biggest MLP, the company said.
"This combination is a significant step in executing MPC's strategy to grow its higher-valued, stable cash flow midstream business, by transforming MPLX into a large-cap, diversified master limited partnership," said President and Chief Executive Gary R. Heminger. "We are very pleased that MPLX and MarkWest will join forces and provide us with opportunities to increase our participation in the U.S. energy infrastructure buildout."
The analysts at Credit Suisse hold an outperform ranking on Marathon Petroleum. Scotia Howard Weil analysts maintain a sector perform rating, while Wells Fargo Securities holds a market perform rating. Of the analysts who cover the stock, 66.7% maintain a buy rating while 33.3% have a hold rating. Shares of Marathon Petroleum have risen about 30% since the start of the year