Maryann Mannen

Maryann T. Mannen
Nationality	American
Occupation	Corporate executive
Title	President, CEO, and Chairman of the Board
Employer	Marathon Petroleum Corporation
Known for	CEO and Chairman of Marathon Petroleum Corporation
Website	[marathonpetroleum.com Official site]

Maryann T. Mannen is an American corporate executive who serves as president, chief executive officer, and chairman of the board of Marathon Petroleum Corporation (NYSE: MPC), the largest petroleum refinery operator in the United States. She assumed the role of chairman effective January 1, 2026, succeeding Michael J. Hennigan, who retired from the position. Mannen leads a company headquartered in Findlay, Ohio, that operates 13 refineries with over 3 million barrels per calendar day of refining capacity, along with an extensive marketing system of branded fuel stations across the United States. In February 2026, she was elected to the board of directors of Prudential Financial Inc. as an independent director, effective May 12, 2026. Her ascent to the top leadership of one of the nation's largest energy companies has placed her among the most prominent executives in the American petroleum industry.

Career

Marathon Petroleum Corporation

Maryann Mannen's career has been closely associated with Marathon Petroleum Corporation, one of the largest integrated downstream energy companies in the United States. Marathon Petroleum traces its origins to a collection of small oil companies in Ohio that merged in 1887 to form The Ohio Oil Company, established in Lima, Ohio. The company grew significantly over the following decades, and in 2011 it was spun off from Marathon Oil Corporation as an independent, publicly traded entity.

Marathon Petroleum's transformation into the nation's largest petroleum refinery operator was cemented by its acquisition of Andeavor on October 1, 2018. The combined company operates 13 refineries across the United States with a total refining capacity exceeding 3 million barrels per calendar day. The company ranked No. 41 on the 2018 Fortune 500 list of the largest United States corporations by total revenue, and it was ranked as the 138th-largest public company in the world in the 2020 Forbes Global 2000.

Marathon Petroleum's operations span refining, marketing, and transportation. Its marketing system includes branded fuel stations across the country operating under the Marathon and ARCO brands, among others. The company also owns the general partner and majority limited partner interest in MPLX LP (NYSE: MPLX), a midstream master limited partnership that owns and operates gathering, processing, and fractionation assets, as well as crude oil and light product transportation and logistics infrastructure.

Rise to CEO

Mannen rose through the executive ranks of Marathon Petroleum over a career spanning multiple leadership positions within the organization. She served as president and chief executive officer of the company, overseeing the full breadth of its refining, marketing, midstream, and retail operations. In this capacity, she was responsible for guiding one of the largest publicly traded energy companies in the United States, with operations that touch virtually every aspect of the downstream petroleum value chain.

Election as Chairman of the Board

On November 4, 2025, Marathon Petroleum Corporation announced that its board of directors had elected Maryann T. Mannen as chairman of the board, effective January 1, 2026. The announcement came as part of a planned leadership transition, with Michael J. Hennigan retiring from the chairman role. Under the new governance structure, John Surma was to continue serving as independent lead director, maintaining the board's independent oversight function alongside Mannen's chairmanship.

The consolidation of the CEO and chairman roles under Mannen represented a significant expression of confidence by the board in her leadership. As chairman and CEO, Mannen assumed full responsibility for both the strategic direction and governance oversight of a company that operates the largest refining system in the United States.

Board Service at Prudential Financial

On February 10, 2026, Prudential Financial Inc. (NYSE: PRU) announced that Maryann Mannen had been elected to its board of directors as an independent director, with the appointment effective May 12, 2026. Prudential Financial is a global financial services company headquartered in Newark, New Jersey, offering insurance, retirement, and investment management products and services.

Mannen's election to the Prudential board reflected her standing as a senior corporate leader with extensive experience in managing a large, complex, publicly traded corporation. The appointment expanded her corporate governance responsibilities beyond the energy sector into financial services, one of the largest industries in the American economy.

Marathon Petroleum Corporation: Company Background

Marathon Petroleum Corporation, the company that Mannen leads, has a corporate history spanning well over a century. The company's origins date to 1887, when several small Ohio-based oil companies consolidated to form The Ohio Oil Company in Lima, Ohio. The Ohio Oil Company quickly became the largest oil producer in the state. By 1889, it had been acquired by the Standard Oil Trust, and six years later its headquarters was relocated to Findlay, Ohio, where Marathon Petroleum remains headquartered today.

In 1906, the company constructed its first oil pipeline, connecting facilities in Martinsville, Illinois, and Preble, Indiana. Following the United States Supreme Court's 1911 order to break up Standard Oil under the Sherman Antitrust Act, The Ohio Oil Company once again became an independent entity. The company expanded its operations by purchasing oil fields outside of Ohio and entered the oil refining business. In 1924, it discovered oil in Texas and acquired Lincoln Oil Refining Company, which included a refinery and 17 brand service stations in Indiana. Several years later, the company acquired Transcontinental Oil, which brought with it refineries, storage facilities, filling stations, and the Marathon product name that would eventually become the corporate identity.

The company operated as a subsidiary of Marathon Oil Corporation until June 2011, when it was spun off as an independent, publicly traded company on the New York Stock Exchange. Following the spinoff, Marathon Petroleum pursued an aggressive growth strategy. In 2013 and subsequent years, the company expanded its refining and retail footprint through a series of strategic acquisitions and operational improvements.

The transformative moment in Marathon Petroleum's modern history came with its acquisition of Andeavor in October 2018, a deal that made the combined entity the largest petroleum refinery operator in the United States. The merger roughly doubled Marathon Petroleum's refining capacity, bringing the total to over 3 million barrels per calendar day across 13 refineries. The acquisition also expanded the company's geographic footprint, adding significant West Coast refining and marketing operations that had previously been operated under the Andeavor and Tesoro brands.

As of 2025, Marathon Petroleum's integrated operations encompass refining and marketing through its direct operations, midstream logistics through its majority-owned subsidiary MPLX LP, and a nationwide network of branded retail fuel stations. The company's common stock trades on the New York Stock Exchange under the ticker symbol MPC, and it is a component of the S&P 500 index.

Recognition

Mannen's election as both chairman and CEO of Marathon Petroleum Corporation placed her at the helm of one of the largest companies in the United States by revenue, as Marathon Petroleum has consistently ranked among the top 50 companies on the Fortune 500 list. Her appointment to the Prudential Financial board of directors in February 2026 further underscored her recognition as a leader in American corporate governance circles.

The announcement of Mannen's chairmanship received coverage in financial and regional news outlets, including those based in the Findlay, Ohio, area where Marathon Petroleum is headquartered. Her Prudential board appointment was reported by multiple financial news services, including Business Wire, TipRanks, MarketScreener, and TradingView, reflecting the significance of the appointment in the financial services and investment communities.

As chairman and CEO of a Fortune 500 company, Mannen is among a small number of women leading major American energy companies, a sector in which female representation at the highest executive levels has historically been limited.

Legacy

Maryann Mannen's leadership of Marathon Petroleum Corporation comes at a consequential period for the American petroleum industry, as the energy sector faces evolving market dynamics, regulatory environments, and the broader global conversation about energy transition. As head of the nation's largest refinery operator, her decisions carry implications for fuel supply, employment, and energy policy across the United States.

Marathon Petroleum, under its succession of leaders including Mannen, has grown from a regional refining operation into a national petroleum powerhouse. The company's acquisition of Andeavor in 2018 was one of the largest deals in the history of the American downstream petroleum sector, and the integration of that acquisition shaped the company that Mannen now leads. With over 3 million barrels per calendar day of refining capacity and a nationwide network of branded fuel stations, Marathon Petroleum's operational scale is unmatched among American refiners.

Mannen's dual role as chairman and CEO, combined with her appointment to the board of Prudential Financial, positions her as a figure of influence in both the energy and financial services industries. The breadth of her corporate responsibilities reflects the interconnected nature of American big business, where leaders of major industrial companies frequently serve on the boards of companies in other sectors, contributing governance expertise and strategic perspective across industries.