Entry, exit, market makers, and the bid-ask spread

The probability of entry and exit of dealers on the NASDAQ National Market (NNM) is significantly affected by trading intensity, volatility and the quoted bid-ask spread. Entry and exit of market makers is a pervasive phenomenon. Largescale entry (exit) is associated with substantial declines (increases) in quoted end-of-day inside spreads, even after controlling for the effects of changes in volume and volatility. The spread changes are larger in magnitude for issues with few market makers; however, even for issues with a large number of market makers, substantial changes in quoted spreads take place. The results are consistent with the competitive model of dealer pricing.