How Aggressive Are High-Frequency Traders?

We study order aggressiveness of market-making high-frequency traders (MM-HFTs), opportunistic HFTs (Opp-HFTs), and non-HFTs. We find that MM-HFTs follow their own group's previous order submissions more than they follow other traders’ orders. Opp-HFTs and non-HFTs tend to split market orders into small portions submitted in sequence. HFTs submit more (less) aggressive orders when the same-side (opposite-side) depth is large, and supply liquidity when the bid–ask spread is wide. Thus, HFTs adhere strongly to the tradeoff between waiting cost and the cost of immediate execution. Non-HFTs care less about this tradeoff, but react somewhat stronger than HFTs to volatility.