UBS AG ( ; SWX: chart_en.html?id=CH0024899483CHF1" target="_blank">UBSN; ) is a diversified global financial services company, with its main headquarters in Basel & Zürich, Switzerland. It is the world's largest manager of private wealth assets, , "the world's biggest manager of other people's money" and is also the second-largest bank in Europe, by both market capitalisation and profitability. UBS has a major presence in the U.S., with its American headquarters located in _New York City's Manhattan borough, (Investment Banking); Weehawken, New Jersey (Private Wealth); and Stamford, Connecticut (Capital Markets). UBS's retail offices are located throughout the United States, and in over 50 other countries. UBS is an acronym, which originated from a predecessor firm, the Union Bank of Switzerland, however UBS ceased to be considered a representational acronym after its 1998 merger with Swiss Bank Corporation.

UBS's global business groups are Private Banking, Investment Banking, and Asset Management. Additionally, UBS is one of the leading providers of retail banking and commercial banking services in Switzerland. Overall invested assets are 3.265 trillion Swiss francs (CHF), shareholders' equity is 47.850 billion CHF and market capitalization is 151.203 billion CHF by end of 2Q 2007.

The AG in the company's name means Aktiengesellschaft, which is the equivalent to a shareholder-based corporation in the USA.

In some ways, UBS has evolved on a similar path to its cross-town rival Credit Suisse. Both are Swiss commercial and retail banks which bought major US investment banks (and in the case of UBS, a leading retail stock broker, PaineWebber).