Prior research concludes that option introductions improve the average liquidity of the underlying stocks. We develop an improved, generalizable test to assess whether market quality changes occur on or near an event date. Applying this method to option listing events, we conclude that options do not systematically improve the market quality of the underlying security; rather, the market quality of the underlying security improves before the listing decision. Hazard model tests indicate that improving liquidity is a selection criterion in the option listing decision. Moreover, these tests suggest that the size of a stock's bid-ask spread is the single most important option listing determinant.

In this paper, we determine whether each bid (ask) quote reflects the trading interest of the specialist, limit order traders, or both for a sample of NYSE stocks in 1991. We then compare Nasdaq spreads with NYSE spreads that reflect the trading interest of the specialist. Our empirical results show that the average Nasdaq spread is significantly larger than the average NYSE specialist spread. We find that, on average, 49% of the difference between Nasdaq and specialist spreads is due to the differential use of even-eighth quotes between Nasdaq dealers and NYSE specialists. We also find that the NYSE specialist spread is significantly larger than the limit order spread, although NYSE specialists and limit order traders are similiar in their use of even-eighth quotes.