Have you heard of algorithmic trading? Wikipedia explains:
In electronic financial markets, algorithmic trading or automated trading, also known as algo trading, black-box trading or robo trading, is the use of computer programs for entering trading orders with the computer algorithm deciding on aspects of the order such as the timing, price, or quantity of the order, or in many cases initiating the order without human intervention.Speed is extremely important in such trading. The computer has to execute the trade at the right moment. "It's all about picking gold coins up off the floor - - only the fastest person is going to get the coins."
Spread Networks decided to stretch a fiber-cable between Chicago and New York to facilitate such trades, and since speed was the primary concern, the company spent (according to Forbes's estimate) $300 million to build the 825-mile route as straight as possible. Information travels 3 milliseconds quicker than the previous fastest route. Spread Networks built the line as quickly and quietly as possible to frustrate any competitors, and at one point had 125 construction crews working at the same time.