Markets consolidate because trading attracts traders. Markets fragment because traders are diverse. Different traders solving different trading problems prefer different market mechanisms. Fragmented markets consolidate when information systems allow traders to see and act upon trading opportunities in all market segments. A segmented market is one in which information systems allow trader-coordinated price formation across various market structures, each designed to provide liquidity to a particular clientele. Some activities in a market segment may have positive or negative external effects on market quality in other segments. Public policy goals may require coordinated regulatory solutions to these externality problems.
Last revised 8/5/96.