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.

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.