Wall Street is a real street in New York City—specifically, near the southern end of Manhattan. In a figurative sense, however, Wall Street is much more: it is a term for the financial sector and the companies that make up that business. This connotation stems from the fact that numerous brokerages and investment banks have traditionally built headquarters on or near the street, all the better to be close to the New York Stock Exchange.
While being on Wall Street is no longer required for a financial-industry firm (many are now spread across the country) or even to trade stocks (which is now mostly done online), the term “Wall Street” still refers to business—the investment business—and the interests, motivations, and attitudes of its participants.