Wells Fargo & Company is an American multinational financial services company with a significant global presence. The company operates in 35 countries and serves over 70 million customers worldwide. It is a systemically important financial institution according to the Financial Stability Board, and is considered one of the "Big Four Banks" in the United States, alongside JPMorgan Chase, Bank of America, and Citigroup.

The company's primary subsidiary is Wells Fargo Bank, N.A., a national bank that designates its Sioux Falls, South Dakota, site as its main office (and therefore is treated by most U.S. federal courts as a citizen of South Dakota). It is the fourth-largest bank in the United States by total assets and is also one of the largest as ranked by bank deposits and market capitalization. It has 8,050 branches and 13,000 automated teller machines and 2,000 stand-alone mortgage branches. It is the second-largest retail mortgage originator in the United States, originating one out of every four home loans, and services $1.8 trillion in home mortgages, one of the largest servicing portfolios in the U.S. It is one of the most valuable bank brands. Wells Fargo is ranked 47th on the Fortune 500 list of the largest companies in the U.S.

In addition to banking, the company provides equipment financing via subsidiaries including Wells Fargo Rail and provides investment management and stockbrokerage services. A key part of Wells Fargo's business strategy is cross-selling, the practice of encouraging existing customers to buy additional banking services. This led to the Wells Fargo cross-selling scandal.

Wells Fargo has international offices in London, Dublin, Paris, Milan, Dubai, Singapore, Tokyo, Shanghai, Beijing, and Toronto, among others. Back-offices are in India and the Philippines with more than 20,000 staff. Notably, Wells Fargo is the first major national U.S. bank to undergo a successful unionization drive. As of 2024, 20 branch locations have joined Wells Fargo Workers United-CWA, a division of Communications Workers of America, in less than a year.

Wells Fargo operates under Charter No. 1, the first national bank charter issued in the United States. This charter was issued to First National Bank of Philadelphia on June 20, 1863, by the Office of the Comptroller of the Currency. Wells Fargo, in its present form, is a result of a merger between the original Wells Fargo & Company and Minneapolis-based Norwest Corporation in 1998. The merged company took the better-known Wells Fargo name and moved to Wells Fargo's hub in San Francisco. At the same time, Norwest's banking subsidiary merged with Wells Fargo's Sioux Falls-based banking subsidiary. Wells Fargo became a coast-to-coast bank with the 2008 acquisition of Charlotte-based Wachovia.

Henry Wells and William G. Fargo, who founded American Express along with John Butterfield, formed Wells Fargo & Company in 1852 to provide "express" and banking services to California, which was growing rapidly due to the California Gold Rush. Its earliest and most significant tasks included transporting gold from the Philadelphia Mint and "express" mail delivery that was faster and less expensive than U.S. Mail. American Express was not interested in serving California.

By the end of the California Gold Rush, Wells Fargo was a dominant express and banking organization in the West, making large shipments of gold and delivering mail and supplies. It was also the primary lender of Butterfield Overland Mail Company, which ran a 2,757-mile route through the Southwest to San Francisco and was nicknamed the "Butterfield Line" after the name of the company's president, John Butterfield. In 1860, Congress failed to pass the annual Post Office appropriation bill, leaving the Post Office unable to pay Overland Mail Company. This caused Overland to default on its debts to Wells Fargo, allowing Wells Fargo to take control of the mail route. Wells Fargo then operated the western portion of the Pony Express.

Six years later, the "Grand Consolidation" united Wells Fargo, Holladay, and Overland Mail stage lines under the Wells Fargo name.