MPLX LP Announces Pricing of Public Offering of 3 Million Common Units

FINDLAY, Ohio, Dec. 3, 2014 - MPLX LP MPLX today announced that it has priced its previously announced underwritten public offering of 3,000,000 common units representing limited partner interests in MPLX at $66.68 per common unit, pursuant to an effective shelf registration statement on Form S-3 previously filed with the Securities and Exchange Commission (SEC). In connection with the offering, MPLX has granted the underwriters a 30-day option to purchase up to 450,000 additional common units. This offering is expected to close on or about Dec. 8, 2014, subject to customary closing conditions.

MPLX expects to use the net proceeds from this offering, including any net proceeds received from an exercise of the underwriters' option to purchase additional common units, to repay borrowings under its revolving credit facility and for general partnership purposes. After giving effect to the repayment, the recently announced acquisition of an additional 30.5 percent interest in MPLX Pipe Line Holdings LP from subsidiaries of Marathon Petroleum Corporation MPC will have been funded approximately 50 percent with debt and approximately 50 percent with equity split between common units offered to the public and new units issued to MPC.

BofA Merrill Lynch, J.P. Morgan, UBS Investment Bank, Wells Fargo Securities, Barclays, Citigroup, and Morgan Stanley are acting as the joint book-running managers for the offering. DNB Markets, Fifth Third Securities, MUFG, PNC Capital Markets LLC and RBS Securities Inc. are acting as co-managers for the offering.

The offering of these securities is being made only by means of a prospectus and related prospectus supplement, which may be obtained for free by visiting the SEC's website at http://www.sec.gov. Alternatively, copies may be obtained by contacting the following, who are acting as representatives of the underwriters:

BofA Merrill Lynch
Attention: Prospectus Department
222 Broadway
New York, NY 10038
Email: dg.prospectus_requests@baml.com

J.P. Morgan
c/o Broadridge Financial Solutions
1155 Long Island Avenue
Edgewood, NY 11717
(866) 803-9204

UBS Investment Bank
Prospectus Department
299 Park Avenue
New York, NY 10171
(888) 827-7275

Wells Fargo Securities
Attn: Equity Syndicate Dept.
375 Park Avenue
New York, NY 10152
(800) 326-5897
Email: cmclientsupport@wellsfargo.com

Barclays
c/o Broadridge Financial Solutions
1155 Long Island Avenue
Edgewood, NY 11717
(888) 603-5847
Email: barclaysprospectus@broadridge.com

Citigroup
c/o Broadridge Financial Solutions
1155 Long Island Avenue
Edgewood, NY 11717
Email: prospectus@citi.com

Morgan Stanley
Attn: Prospectus Department
180 Varick Street, 2^nd Floor
New York, NY 10014
(866) 718-1649
Email: prospectus@morganstanley.com

This news release shall not constitute an offer to sell or a solicitation of an offer to buy any securities, nor shall there be any sale of these securities in any state or jurisdiction in which such an offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

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About MPLX LP

MPLX is a fee-based, growth-oriented master limited partnership formed in 2012 by Marathon Petroleum Corporation to own, operate, develop and acquire pipelines and other midstream assets related to the transportation and storage of crude oil, refined products and other hydrocarbon-based products. Headquartered in Findlay, Ohio, MPLX's assets consist of a 99.5 percent equity interest in a network of common carrier crude oil and products pipeline assets located in the Midwest and Gulf Coast regions of the United States and a 100 percent interest in a butane storage cavern located in W.Va. with approximately 1 million barrels of natural gas liquids storage capacity.

Investor Relations Contacts:
Geri Ewing (419) 421-2071
Teresa Homan (419) 421-2965

Media Contacts:
Angelia Graves (419) 421-2703

This press release contains forward-looking statements within the meaning of federal securities laws. These forward-looking statements are based on management's current expectations and relate to, among other things, plans regarding the use of proceeds from this offering of common units. Such forward-looking statements are not guarantees of future performance and are subject to risks, uncertainties and other factors, some of which are beyond the issuer's control and are difficult to predict. Factors that could cause MPLX actual results to differ materially from those in the forward-looking statements include: the adequacy of capital resources and liquidity, including, but not limited to, availability of sufficient cash flow to pay distributions and execute on business plans; the timing and extent of changes in commodity prices and demand for crude oil, refined products, feedstocks or other hydrocarbon-based products; volatility in and/or degradation of market and industry conditions; completion of pipeline capacity by competitors; disruptions due to equipment interruption or failure, including electrical shortages and power grid failures; the suspension, reduction or termination of MPC's obligations under commercial agreements with MPLX; the ability to successfully implement growth strategies, whether through organic growth or acquisitions; modifications to earnings and distribution growth objectives; state and federal environmental, economic, health and safety, energy and other policies and regulations; other risk factors inherent to our industry; and the factors set forth under the heading "Risk Factors" in MPLX's Annual Report on Form 10-K for the year ended Dec. 31, 2013, filed with the Securities and Exchange Commission (SEC). In addition, unpredictable or unknown factors not discussed here or in MPLX's Form 10-K could also have material adverse effects on forward-looking statements.