Complex sentence: Trading systems slow down a direct exchange feed whenever they want, and the phantom orders do not need to be in a particular stock; they can be in any of the securities that cohabit the particular price (market data) feed.
Split into simpler sentences: Trading systems slow down a direct exchange feed whenever they want, and the phantom orders do not need to be in a particular stock. They can be in any of the securities that cohabit the particular price (market data) feed.