What do you do when you've conquered Wall Street? You become mayor of the city the famous financial district calls home. After leading his financial news and information company to success, Michael Bloomberg left to run the Big Apple. His namesake company remains a leader in the market for business media. Its core Bloomberg Professional Service offering is accessed through terminals that provide real-time financial news, market data, and analysis. The firm also has a syndicated news service, publishes magazines (including Bloomberg Businessweek ), and disseminates business information via Bloomberg Television, radio, and the Web. Michael Bloomberg founded the company in 1981; he owns a majority of the firm.