Tick Size Constraints, Market Structure, and Liquidity

Abstract

We argue that a one-penny minimum tick size for all stocks priced above $1 (SEC rule 612) encourages high-frequency trading and taker/maker–fee markets. We find that non-high frequency traders (non-HFTers) are 2.62 times more likely than HFTers to provide best prices, thereby establishing price priority. The larger relative tick size for low priced stocks, however, constrain non-HFTers from providing better prices and HFTers’ speed advantage helps them establish time priority over non-HFTers. Non-HFTers enter the taker/maker market more frequently than HFTers, because they can bypass tick size constraints by paying a fee to the exchange. The incentive to pay a fee is stronger when relative tick size is high. When stock splits increase relative tick size, liquidity does not improve and volume shifts to the taker/maker market. Our results indicate recent proposals to increase tick size will not improve liquidity. Instead, they will encourage high frequency trading and lead to proliferation of markets that bypass the tick size constraints.

Keywords: price constraints, high-frequency trading, maker/taker fees, liquidity, tick size non-price competition