Electronic Trading: Electronic Communications Networks (ECNs)

An electronic communication network (ECN) is an electronic system that attempts to facilitate (for market makers) or eliminate (for individual investors) third party orders entered by a client's brokerage to be executed in whole or in part. ECNs network major brokerages and traders so that they can trade between themselves without having to go through a middleman. The advantage of an ECN is that it displays orders in real time, whereas on the NYSE, most investors are limited to only viewing the best bid and ask prices. (For related reading, see Direct Access Trading Systems and Introduction To Level II Quotes.)

There are several variations of ECNs in the market, each of which are slightly different. Here are some of the more popular ones and a summary of their basic characteristics:

Instinet
Instinet was the first ever ECN, founded in 1969. It was originally a way for brokerages to display bid and ask prices for practically every stock in North America and abroad and was first used by institutions to transact with each other. Today it also includes a select group of smaller brokerages. Instinet is used to execute a large proportion of orders on Nasdaq and is primarily entered by market makers. Because of this exclusive access many of the large block orders on Nasdaq stocks are traded through Instinet. More recently, Instinet has tried to level the playing field by lowering access fees and allowing individual investors and small firms to access its orders.

SelectNet
This electronic system is primarily used for trading between market makers. SelectNet is known as a negotiable system, which means that market makers may or may not execute your order immediately, as on other ECNs, although they are required to execute immediately if the order is at the advertised price and it appears on the market maker's screen. SelectNet is popular among traders because orders can be preferenced, which allows a trader to isolate and trade with a particular market maker. This is advantageous because traders can target market makers who are active in the stock he/she wants to trade. This way the trader will get immediate attention, which usually results in a faster execution.

There are a few networks that are used to facilitate trading on Nasdaq stocks. One, the small order execution system (SOES), we will discuss next, but there are also other ECNs offered by Bloomberg, Terra Nova and others.