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	Official site

Maryann T. Mannen is an American corporate executive who serves as the president, chief executive officer, and chairman of the board of Marathon Petroleum Corporation (NYSE: MPC), the largest petroleum refining company in the United States. She assumed the role of chairman on January 1, 2026, succeeding Michael J. Hennigan, who retired from the position. Mannen's leadership places her at the helm of a company that, following its acquisition of Andeavor in 2018, operates 13 refineries with a combined capacity exceeding three million barrels per calendar day. In February 2026, she was elected to the board of directors of Prudential Financial Inc. as an independent director, effective May 12, 2026. Under Mannen's leadership, Marathon Petroleum continues to rank among the largest corporations in the United States, having appeared at No. 41 on the 2018 Fortune 500 list by total revenue.

Career

Marathon Petroleum Corporation

Maryann Mannen rose through the executive ranks of Marathon Petroleum Corporation, one of the largest integrated downstream energy companies in the United States. Marathon Petroleum was established as a wholly owned subsidiary of Marathon Oil before becoming an independent publicly traded company through a corporate spin-off in 2011. The company is headquartered in Findlay, Ohio, where its predecessor entities have maintained operations since 1895.

Marathon Petroleum's operations encompass petroleum refining, marketing, retail, and midstream transportation. The company's marketing system includes branded locations across the United States, operating under both the Marathon and ARCO brands. MPC also owns the general partner and majority limited partner interest in MPLX LP, a midstream company that owns and operates gathering, processing, and fractionation assets, as well as crude oil and light product transportation and logistics infrastructure.

The company underwent a major transformation in 2018 with its acquisition of Andeavor (formerly Tesoro Corporation), which was completed on October 1, 2018. The merger made Marathon Petroleum the largest petroleum refinery operator in the United States, with 13 refineries and over three million barrels per calendar day of total refining capacity. This strategic consolidation positioned the company as a dominant force in the American refining sector. At the time of the merger, analysts noted that the deal addressed key strategic considerations for the company's downstream operations.

Marathon Petroleum's scale and financial performance have placed it consistently among the largest publicly traded companies globally. The company ranked No. 41 on the 2018 Fortune 500 list of the largest United States corporations by total revenue. In the 2020 Forbes Global 2000, Marathon Petroleum was ranked as the 138th-largest public company in the world. The company trades on the New York Stock Exchange under the ticker symbol MPC and is a component of the S&P 500 index.

President and Chief Executive Officer

Mannen served as president and chief executive officer of Marathon Petroleum Corporation, leading the company's extensive refining, marketing, and midstream operations. In her capacity as CEO, she oversaw a company with a vast operational footprint that includes refining facilities, branded fuel stations, and significant midstream infrastructure through the MPLX LP partnership.

The company's refining operations, which Mannen oversees as CEO, span multiple facilities across the United States. Marathon Petroleum's refineries process crude oil into a variety of petroleum products, and the company's marketing operations distribute fuel through thousands of branded retail locations. The company also markets gasoline formulated with STP additives through its branded station network.

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 election came as Michael J. Hennigan, who had been serving as executive chairman, retired from the position. The transition was structured to ensure continuity of leadership, with John Surma continuing in his role as independent lead director of the board. With this appointment, Mannen assumed the combined roles of president, CEO, and chairman, consolidating the company's top leadership positions.

The announcement was reported by local media in Findlay, Ohio, Marathon Petroleum's headquarters city, as well as by national financial media outlets. Mannen's elevation to chairman represented a significant milestone in her career at the company, positioning her as the sole leader of one of the largest energy companies in the United States.

Prudential Financial Board Appointment

On February 10, 2026, Prudential Financial Inc. (NYSE: PRU) announced that Maryann Mannen had been elected to the company's board of directors as an independent director. The appointment is effective May 12, 2026, at which point she will also join the board's Audit Committee and Investment Committee.

Prudential Financial, one of the largest financial services companies in the world headquartered in Newark, New Jersey, noted Mannen's extensive leadership experience in its announcement of the election. Financial analysts and news services widely reported the appointment, with coverage noting her concurrent role as president, CEO, and chairman of Marathon Petroleum Corporation.

The Prudential board appointment expanded Mannen's corporate governance responsibilities beyond Marathon Petroleum, placing her in an oversight role at a major financial institution with global operations in insurance, investment management, and other financial services.

Marathon Petroleum Corporation Background

Marathon Petroleum Corporation traces its corporate lineage to a number of small oil companies in Ohio that consolidated in 1887 to form The Ohio Oil Company, established in Lima, Ohio. The Ohio Oil Company became the largest oil producer in the state. By 1889, the company was acquired by the Standard Oil Trust, and six years later its headquarters was relocated to Findlay, Ohio, where Marathon Petroleum remains headquartered.

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 that Standard Oil be dissolved under the Sherman Antitrust Act, Ohio Oil again became an independent company. It subsequently expanded its operations by acquiring oil fields outside of Ohio and began petroleum refining activities.

A pivotal year in the company's history was 1924, when Ohio Oil discovered oil in Texas and acquired the Lincoln Oil Refining Company. The Lincoln acquisition included a refinery and 17 branded service stations in Indiana. Several years later, Ohio Oil acquired Transcontinental Oil, a deal that included refineries, storage facilities, filling stations, and—critically—the Marathon product name that would eventually become the company's identity.

The modern Marathon Petroleum Corporation was created on June 30, 2011, when Marathon Oil Corporation completed the spin-off of its downstream refining, marketing, and transportation operations into an independent publicly traded company. This spin-off allowed Marathon Petroleum to operate independently and pursue its own strategic direction in the downstream petroleum sector.

The 2018 acquisition of Andeavor marked the most transformative event in the company's modern history. The merger, completed on October 1, 2018, brought together two of the largest independent refining companies in the United States. The combined entity's 13 refineries and capacity exceeding three million barrels per calendar day established Marathon Petroleum as the preeminent refining company in the nation. The company's extensive refining network processes crude oil into transportation fuels, petrochemicals, and other petroleum-derived products distributed through its branded station network.

Marathon Petroleum's midstream operations are conducted primarily through MPLX LP, in which MPC holds the general partner interest and a majority limited partner interest. MPLX owns and operates a network of gathering, processing, and fractionation assets, along with crude oil and light product transportation and logistics infrastructure that supports both Marathon Petroleum's refining operations and third-party customers.

The company files annual reports with the U.S. Securities and Exchange Commission, providing detailed financial and operational disclosures to investors and regulators.

Recognition

Maryann Mannen's appointment as CEO and subsequently as chairman of Marathon Petroleum Corporation placed her among the most prominent women leading Fortune 500 companies in the United States. Marathon Petroleum's ranking at No. 41 on the 2018 Fortune 500 list and its position as the 138th-largest public company in the world in the 2020 Forbes Global 2000 underscore the scale of the enterprise under her leadership.

Her election to the Prudential Financial board of directors in February 2026 further recognized her standing in American corporate governance. Prudential's announcement specifically identified her for service on the board's Audit Committee and Investment Committee, positions that reflect confidence in her financial and operational expertise.

The transition of Marathon Petroleum's chairmanship to Mannen received coverage from financial news services, industry publications, and local media in the Findlay, Ohio, region, reflecting the significance of the leadership change at one of the nation's largest energy companies. Multiple financial analysis platforms reported on her Prudential board election, noting her dual corporate leadership roles as indicative of her prominence in the American business community.