Filed by Citigroup Inc. Pursuant to Rule 425
under the Securities Act of 1933

Subject Company: Grupo Financiero Banamex Accival S A De C V
Commission File No. 082-03325

Date: May 17, 2001

In connection with the proposed transaction, Citigroup expects to file a registration statement on Form S-4 with the Securities and Exchange Commission. Investors and security holders are advised to read the registration statement when it becomes available because it will contain important information. Investors and security holders may obtain a free copy of the registration statement (when available) and other documents filed by Citigroup with the SEC at the SEC's web site at <http://www.sec.gov>. Free copies of the registration statement (when available) and other documents filed by Citigroup with the SEC may also be obtained from Citigroup by directing a request to Citigroup Inc., 399 Park Avenue, New York NY 10043, Attention: Treasurer (212-559-1000).

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For immediate release
Citigroup Inc. (NYSE: C)
Banacci (BMV: BANACCI.O)
May 17, 2001

BANACCI TO INTEGRATE WITH CITIGROUP

Banacci Shareholders to be offered $6.25 Billion in Citigroup Shares and $6.25 Billion in Cash for a Total of $12.5 Billion

Transaction Expected to Be Accretive to Citigroup Earnings In First Year

Banacci and Citigroup's Mexican Operations to be Combined Under the Banamex brand

Together to Serve the Fast-Growing Hispanic Community Throughout North America

Banacci's Hernández and Harp will join Citigroup Board Citigroup's Rubin, Menezes and Rhodes to join Banacci and Banamex Boards

Mexico City, Mexico and New York, New York, May 17, 2001 — Grupo Financiero Banamex-Accival ("Banacci"), Mexico's top financial institution, and Citigroup, the preeminent global financial services company, announced today that they have reached an agreement through which Banacci, and all its direct and indirect subsidiaries, will integrate with Citigroup's global operations.

Banacci shareholders will receive $6.25 billion in cash and 126,877,791 Citigroup shares which, based on a closing price of $49.26 on May 11th, have a value of $6.25 billion - for a total transaction value of $12.5 billion.

The transaction grants equal treatment to all Banacci shareholders, and the tender offer is for 100% of Banacci shares. Shareholders representing at least 51% of Banaccis shares have agreed to tender their shares prior to the tender offer. Citigroup will apply to have its shares listed on the Mexican Stock Exchange. If approved, Citigroup will be the first international company to be so listed.

Under the terms of the transaction, Banacci and Citigroup's operations in Mexico will be integrated, and will conduct business under the "Banamex" brand name.

"Globalization is an undeniable reality, full of opportunities," said Roberto Hernández, Chairman of the Board of Banamex. "Our integration with Citigroup, the most important financial institution worldwide, assures that Mexico possesses a strong bank that will continue to compete effectively on the changing world stage, and that the Mexican companies and consumers can continue to be served by an exceptionally strong and competitive global bank."

"Mexico and the United States have become increasingly integrated in terms of the flow of goods, services and capital. This combination positions both Banacci and Citigroup to capitalize on this important trend, and thus is a natural next step for both of our companies," said Sanford I. Weill, Chairman and Chief Executive Officer of Citigroup. "Mexico is one of the most important markets in the world. As the premier financial institution in Mexico, with a tremendous brand and an excellent record of profitability and customer service, Banacci is the ideal partner for our company as we work to strengthen our presence in this country. We are extraordinarily impressed with Banamex's management, and look forward to creating with our new partners the strongest financial institution in Mexico, significantly enhancing our overall franchise. We will also work together to develop our position in the rapidly growing Hispanic market in other parts of North America."

The transaction, which has been unanimously approved by the Boards of Directors of both companies, is subject to a number of regulatory approvals and is expected to close in the fourth quarter.

Roberto Hernández, Chairman of Banamex, and Alfredo Harp, Chairman of Banacci, will maintain their current positions and join the Citigroup Board. Citigroup's management, including Robert Rubin, Victor Menezes and William Rhodes, will have representation on Banacci and Banamex's boards

A management team will be drawn from both organizations, headed by Manuel Medina Mora, CEO of Banacci, who, upon closing, will also become CEO of Banamex and who will report to Citigroup's Victor Menezes, head of Citigroup's Emerging Markets' business.

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Citigroup (NYSE:C), the preeminent global financial services company, provides some 120 million consumers, corporations, governments and institutions in more than 100 countries with a broad range of financial products and services, including consumer banking and credit, corporate and investment banking, insurance, securities brokerage and asset management. Major brand names under Citigroup's trademark umbrella are Citibank, CitiFinancial, Primerica, Salomon Smith Barney, and Travelers. Additional information may be found at: www.citigroup.com.

Grupo Financiero Banamex-Accival is Mexico's leading financial group. Following a universal banking strategy, the Group offers a variety of financial services to companies and individuals, which include commercial and investment banking, insurance, and fund management. Banamex, founded in 1884, is Mexico's largest commercial bank in terms of equity and earnings. The Bank has an extensive distribution network of more than 1,300 branches and 3,000 ATM's located throughout the country.

Live Webcast Alert:

A webcast of an 8:30 a.m. (ET) investment community meeting to review the transaction will be available on the Citigroup website. To gain access to the webcast, which will be "listen-only," go to www.citigroup.com <http://www.citigroup.com>. Please log on to the website at approximately 8:00 a.m. A replay of the webcast will also be available at www.citigroup.com <http://www.citigroup.com>, as will a copy of the investment community presentation.

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On May 17, 2001, Citigroup and Grupo Financiero Banamex-Accivel ("Banacci") held a meeting for the investment community to discuss the integration of Banacci, and all of its direct and indirect subsidiaries, with Citigroup's global operations. A copy of the slides shown at the meeting and available on the webcast follows.