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.

We study odd-lot trading and determine if an odd-lot trade results from odd-lot orders or if odd-lots are a result of orders broken into multiple trades. We confirm that odd-lot transactions contribute to price discovery. Our finding that odd-lot transactions contain substantial information is not being driven by orders that are originally larger than 100 shares and subsequently divided into odd-lot transactions. We further find that odd-lot transactions resulting from odd-lot orders add more to price discovery than odd-lot transactions resulting from orders for 100 or more shares. Additionally, we find that more price contribution occurs when non-high frequency traders trade in an odd-lot transaction.

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.

1-share trades are the most common odd lot trade size, accounting for 9.62% of all odd lot transactions and 3.65% of all trades on NASDAQ in 2012. While 50.41% of 1-share trades result from broken orders, 34.89% of 1-share trades are intentional. We provide substantial evidence that traders use 1-share trades to “ping” for hidden liquidity. In particular, our results indicate that 1-share trades are disproportionately aggressive and also execute against hidden liquidity more than any other odd lot trade size. We also find a relative increase in trading immediately following a 1-share trade. Our results are in line with Clark-Joseph (2014), who suggests that traders may use small, unprofitable trades to detect information from other traders. Specifically, 1-share trades represent the minimum cash outlay necessary to trade, while simultaneously producing the smallest possible effects on a market maker's inventory, and in turn, a security's price.