A loose term used in business for 'Capital Markets' and 'Money Markets'. Capital markets are financial centers where funds, or capital, can be raised for commercial ventures. Money Markets are the parts of a financial centre trading in short term securities, foreign exchange, and gold.
Sinister, dark, dangerous, and a little intimidating. Staffed by overpaid people in flash suits - who use their knowledge to earn massive bonuses. Always in a city centre to make people's life hell when commuting - well if you want the big bucks, then you're going to have to suffer to get at them. PS - it's the capital and money markets we all know and love. (Go serious on this one.)