A cross connect is a dedicated physical cable that joins the equipment of two parties inside the same data center. In trading it is the link between a firm's server cabinet and an exchange's network, a broker, a market data vendor or a telecommunications carrier. The cable is usually optical fiber, sometimes copper, and it is installed and maintained by the data center operator, which charges a set-up fee and a monthly rental.
Cross connects are the last few meters of a colocation arrangement. Because the path is private and passes through no public network or intermediate device, it gives the shortest and most predictable delay available, which matters for low latency strategies. Exchanges commonly equalize cable lengths so that every customer's connection to the matching engine takes the same time. Firms normally order two or more cross connects over separate routes, so that a single cable fault does not cut them off from the market.