Order flow is toxic when it adversely selects market makers, who may be unaware they are providing liquidity at a loss. We present a new procedure to estimate flow toxicity based on volume imbalance and trade intensity (the VPIN toxicity metric). VPIN is updated in volume-time, making it...

We investigate how and why relative tick sizes influence traders' order strategies, and how this affects liquidity provision in the market. Using unique NYSE data, we find that a larger relative tick size benefits HFT market makers: they leave orders in the book longer, trade more aggressively,...