Earlier quoted context omitted.
I disagree with this description. Retail flow is primarily uninformed - "noise", not "signal" (i.e. "alpha" in finance speak). Retail traders might trade based on Twitter news, Reddit suggestions, weather, gut feeling, sudden money needs, ... Institutional traders are big and slow and they have long-term alpha (if any), I don't think they'd generate much worry for HFTs/market makers... The real worry is other HFTs, s…
That makes sense too (avoiding competition). But it's not what the quoted article says. Institutional trading (like mutual funds) certainly is a problem for market makers: > Sometimes, when a customer buys 100 shares at $100.01, it then buys another 100 shares at $100.02, and another 100 shares at $100.03, and keeps going until it has bought 10,000 shares and pushed the price up dramatically. The market maker who sol…
Still, I disagree. Even a large order won't "move" the market by itself (unless you're the Fed). At best, it might trigger a flash crash (we've seen a few of these in the past few years), where liquidity temporarily dries up (HFT market makers remove their passive orders, until they figure out what the hell is going on, precisely because they already predict cases like this) but comes back as soon as human traders figure out that nothing is going on (and the price has no reason to move).
More likely, a large order might blow through a few layers of the order book, which is good for market makers - instead of selling it at $100.01 (which is the "best", i.e. "lowest" price), you're selling it at $100.02 (i.e. you're making more money than your fellow market makers). In general, if you're an "institutional" (or otherwise big & slow) trader trading "large" orders (relative to the standard market volume), you're trying hard to disguise your intents. If HFTs know that you will buy the next 100 shares, they'll just sell it to you for $100.09 or more!