1. HFT market makers creating liquid markets that won’t otherwise exist. 2. Dramatic lowering of bid-offer spreads and, thus, transaction costs to liquidity ta

1. HFT market makers creating liquid markets that won’t otherwise exist. 2. Dramatic lowering of bid-offer spreads and, thus, transaction costs to liquidity takers (eg retail investors). 3. No-arbitrage pricing: safe to assume that virtually any easily-tradable instument is fairly priced, otherwise would’ve been quickly arbitraged. Has not always been this way. 4. Driving innovation by paying for technologies/solutions that nobody except HFTs would buy at the time.