The systems by which stocks are traded have also evolved, the second half of the twentieth century having seen the advent of Electronic Communication Networks (ECNs). These are essentially large proprietary computer networks on which brokers could list a certain amount of securities to sell at a certain price (the asking price or “ask”) or offer to buy a certain amount of securities at a certain price (the “bid”).
ECNs and exchanges are usually known to traders by a three- or four-letter designators, which identify the ECN or exchange on Level II stock screens. The first of these was Instinet (or “inet”), which was founded in 1969 as a way for major institutions to bypass the increasingly cumbersome and expensive NYSE, also allowing them to trade during hours when the exchanges were closed. Early ECNs such as Instinet were very unfriendly to small investors, because they tended to give large institutions better prices than were available to the public. This resulted in a fragmented and sometimes illiquid market.
The next important step in facilitating day trading was the founding in 1971 of NASDAQ — a virtual stock exchange on which orders were transmitted electronically. Moving from paper share certificates and written share registers to “dematerialized” shares, computerized trading and registration required not only extensive changes to legislation but also the development of the necessary technology: online and real time systems rather than batch; electronic communications rather than the postal service, telex or the physical shipment of computer tapes, and the development of secure cryptographic algorithms.
These developments heralded the appearance of “market makers”: the NASDAQ equivalent of a NYSE specialist. A market maker has an inventory of stocks to buy and sell, and simultaneously offers to buy and sell the same stock. Obviously, it will offer to sell stock at a higher price than the price at which it offers to buy. This difference is known as the “spread”. It is of no importance to the market-maker whether the price of a stock goes up or down, as it has enough stock and capital to constantly buy for less than it sells. Today there are about 500 firms who participate as market-makers on ECNs, each generally making a market in four to forty different stocks. Without any legal obligations, market-makers were free to offer smaller spreads on ECNs than on the NASDAQ. A small investor might have to pay a $0.25 spread (e.g. he might have to pay $10.50 to buy a share of stock but could only get $10.25 for selling it), while an institution would only pay a $0.05 spread (buying at $10.40 and selling at $10.35).