The part about spreads being smaller because machines are making markets is true, but there are important caveats. The one that comes to mind first is that the

The part about spreads being smaller because machines are making markets is true, but there are important caveats. The one that comes to mind first is that the tight market is only there for small quantities. If you want to trade in size, then you are out of luck. Machine based market making tends to work well when markets are operating "normally". When some regime-changing news comes out, it's not uncommon for the over-fit algorithms to perform badly so the managers just turn them off. I.e. liquidity disappears just when it's needed most. https://www.wsj.com/articles/thinning-liquidity-in-key-futures-market-worries-traders-11553515200 https://www.wsj.com/articles/thinning-liquidity-in-key-futur...