1. A method for trading quotes relating to financial instruments received from quoting firms in a computerized trading system having a plurality of independent trading environments, each of the independent trading environments having (i) a communication network, (ii) a matching engine executed by a server, and (iii) plural instances of an express interface application executed by the server, each express interface application being associated with a particular quoting firm, wherein trading in the financial instruments is divided among the independent trading environments on the basis of symbols associated with the traded financial instruments and each independent trading environment is configured to process quotes from one or more trading symbols out of all the trading symbols tradable on the trading system, the method comprising: receiving quotes from a particular quoting firm at each express interface application; placing, by the express interface applications, the quotes received from the respective quoting firms in areas of a shared memory each reserved for quotes from a particular respective one of the quoting firms; polling, by the matching engine, the areas of the shared memory in a round-robin manner, such that, when the matching engine finds a quote or quotes in an area of the shared memory, the matching engine completes processing of the quote or quotes in the area before polling a next area of the shared memory; and the matching engine, upon completion of polling all areas of the shared memory, checking a network port of the matching engine to service messages received over the network, before repeating the polling of the shared memory areas for quotes.