Recent proposals to raise the tick size on small stocks bring attention to the role played by market structure in shaping the trading environment and ultimately in capital formation. In this paper, we look at the how the relative tick size influences liquidity and the biodiversity of trader interactions in the market. Using unique order-level Our empirical analysis of relative tick size effects focuses on one such fundamental structure issue, and in this concluding section we discuss the implications of our results for the current debate regarding raising minimum tick sizes for small firms.Advocates of raising the tick size stress the linkage from tick size to market maker profits. Two avenues are suggested for how these profits would then drive additional investor trading. First, more profitable market making could lead to an increase in liquidity provision for the stocks, which would attract additional volume from investors who are wi!ling to trade liquid stocks but shy away from illiquid ones. Second, the higher profitability of market making operations at sell-side firms could lead to nrc>e>T<>r coverage, enhanced promotion by and increased willingness of companies to go public. In particular, the argument is that the fall in tick sizes to decimals has both reduced incentives to post limit orders and dramaticaUy reduced compensation to market making in those stocks. The resulting illiquidity has made such stocks unattractive to investors and, combined with the fall in analyst coverage of small firms, also made listing new stocks unattractive to issuers. Raising the minimum tick size addresses these concerns by improving the trading environment for small stocks.Our analysis essentially follows the first linkage above (tick size to liquidity to volume) by looking at the trading environment for stocks with different relative tick sizes. In our analysis, stocks in our Gl sample face relative tick si:zes that are approximately 10 times larger than those of the control stocks, G2 face relative tick sizes that are 4 times larger, and G3 stocks face relative ticks that are 2 times larger. Because our Maureen O'Hara (mo19@cornell.edu) and Gideon Saar (gs25@cornell.edu) are from the Johnson Graduate School of Management, Cornell University, and Zhuo Zhong (zz225@cornell.edu) is from the Department of Economics, Cornell University. We thank Viral Acharya, Simon Gervais, Charles Jones, and Andrew Lofor helpful comments on a presentation of this project at FINRA's Economic Advisory Committee meeting. NYSE provided us with data and financial support for analyzing the data. All conclusions are those of the authors and do not represent the views of the NYSE. 1 analysis controls for other factors that also affect liquidity (e.g., market capitalization, industry, investor clientele, and volatility), we can extract the effects of tick size on liquidity and the liquidity provision process. Does a larger relative tick size increase liquidity? We find little evidence of this. Percentage spreads are not significantly di...