The central question in securities-market structure is whether investors are better served by human-mediated markets, such as the specialist system of the New York Stock Exchange, or by electronic markets, such as NASDAQ and the Electronic Communication Networks. The Securities and Exchange Commission's recent Regulation NMS, although it purports to...

The proposal of the Securities and Exchange Commission for market structure reform, like so many other recent SEC initiatives, seems entirely ad hoc.

At an AEI conference last June, Professor Kenneth M. Lehn and his colleagues presented a ground-breaking paper that compared the effect of market stress—when the markets receive new positive or negative information—on the bid-ask spreads in the NYSE, NASDAQ, and the electronic communications networks (ECNs). The June paper indicated that...

The authoraddresses whether the Securities and Exchange Commission should permit the electronic order-matching markets to compete with the New York Stock Exchange.