Pemex had total assets worth $101.8 billion in December 2019[2] and as of 2009 was Latin America's second largest enterprise by annual revenue, surpassed only by Petrobras (the Brazilian national oil company).

By the early 20th century, commercial quantities of oil were being extracted and refined by subsidiaries of the British Pearson and American Doheny companies and had attracted the attention of the Mexican government who then claimed all mineral rights for the state as part of its Constitution.

On March 18, 1938, citing Article 27 of the Constitution of 1917, President Cárdenas embarked on the state-expropriation of all resources and facilities, nationalizing the United States and Anglo–Dutch operating companies.

However, in retaliation, many foreign governments closed their markets to Mexican oil until the Allies demand for petroleum in World War II caused the boycott to be dropped.

To help capitalize the company, former President Vicente Fox brought forward the possibility of making shares of Pemex available to Mexican citizens and pension funds, to complement a current project-specific investment setup known as "Proyectos de Inversión Diferida En El Registro del Gasto" (Deferred Investment Projects in the Expenditure Registry).

[11] The proposal, which intended to alleviate Pemex's tax burden and create a substantial budget increase, met opposition in Congress.

In June 2009, Pemex has asked for an extra $1.5 billion state aid to finance oil fields investments, reported Bloomberg.

His comments came after Petrobras and London-based BP said they made a "giant" oil find of as much as 3 billion barrels (480×10^6 m3) in the Gulf of Mexico, southeast of Houston.

[18] Also in July 2021, the SENER appointed Pemex as the operator for the Zama oil field which was originally discovered by Talos Energy in 2017.

[19][20] In September that year, Talos disputed the governments decision, since Pemex doesn't have the required $2 billion for the oil fields development.

[32] In June 2023, Pemex received bids for the renewal of the Dos Bocas wastewater treatment plant (PTE) which was originally built in 1970 and is no longer capable of treating the oily waters.

[35] In September 2023, it was announced that Pemex would receive capital allocations from the federal government of Mexico to assist in paying off over $11 million in accumulated debt.

[36][37] Proponents of Calderón's energy policy stated that Pemex lacks the equipment, technology and financial means to explore for new reserves in deep water or shale gas; hence, a reform to Mexican law is needed.

[49] Pemex spent $100 million to clean up the spill and avoided most compensation claims by asserting sovereign immunity as a state-run company.

[50] On November 19th, 1984, a series of BLEVE's at a Pemex LPG storage facility occur in the heavily populated outskirts of San Juan Ixhuatepec, near Mexico City, resulting in the deaths of around 500-600 residents and up to 7000 injured by the explosions, ensuing fire and shrapnel from exploding tanks.

[59] On September 24, 2016, a fire broke out on the oil tanker "Burgos", off the coast of Boca del Río, Veracruz, forcing all the crew (31 members) to be evacuated safely.

Military and police forces were present during the event for several hours before the explosion but were unable to stop the people from stealing fuel.

There was one person killed and at least 13 others were injured[69] In 2009, the U.S. Justice Department reported that some U.S. refineries had bought millions of dollars' worth of oil stolen from Mexican government pipelines.

Homeland Security Department will return $2.4 million to Mexico's tax administration—the first money seized during a binational investigation into smuggled oil that authorities expect to lead to more arrests and seizures.

In 2010 the former president of Houston-based Trammo Petroleum was sentenced to three years of probation and fined $10,000 after pleading guilty to conspiracy to receive stolen goods.

[71] This included the death of a person who was refused medical service at one of Pemex's hospitals because his son had just been sacked for belonging to this union, the Unión Nacional de Técnicos y Profesionistas (shorthand UNTyPP).

[75] In November 2021, the arrest of former CEO Carlos Trevino was ordered after he did not show for his hearing, in which he was being charged with criminal association and money laundering.

[76] In January 2022, Lozoya was formally charged with money laundering, bribery and criminal association, which could amount to 39 years in prison.

These range from political contributions to the Institutional Revolutionary Party (PRI) (over $200 million), "no show" jobs – individuals who receive a salary while performing no duties – various forms of fraud, embezzlement and even under-the-table fuel sales.

Back in 2010–2012, Emilio Lozoya Austin was part of the PRI's team supporting Enrique Peña Nieto (EPN) in his presidential campaign.

In 2017, Brazilian newspaper O Globo claimed that Odebrecht helped finance EPN's presidential campaign, by giving $10 million to Emilio Lozoya as a bribe during times close to the 2012 elections.

The news of the controversy surfaced in 2017,[79] revealing Lozoya bought a $38 million house with a single payment even before he was named a director of Pemex.