why do traders need to pay attention to tick size 
for active traders tick size is crucial in determining liquidity position sizes and potential risks and rewards for example a high tick size means each tick change equals a larger profit or loss traders may opt for smaller position sizes if the tick size is high can stocks trade between tick sizes yes stocks can trade below the official tick size of 0 01 orders can be priced in sub penny increments if they are priced to execute against a particular hidden order or used in a retail price improvement program where a retail investor s order is executed at a slightly better price than the best available public quote in dark pools private exchanges for trading securities not accessible by the public investing community and through internalization where a broker might fill an order from their own inventory transactions can sometimes occur at sub penny increments however these trades are not publicly displayed 