Earlier quoted context omitted.
I definitely don't know enough about trading. So please forgive if this is just naive. From what I gather, the problem is matching sellers to buyers. Sellers list what they're looking to buy, and the price they're willing to pay. Buyers list what they're willing to sell, and at what price. Let's say each offer is valid for 100 ms (that's a reasonably short time span, no immense risk for the entity making the offer).…
Most HFTs are market makers, meaning they are willing to buy or sell any of the stuff they trade at any time. They provide the service of assuming risk that they don't really want. If some non-HFT participants show up to a limit order book, they could transact with each other, but it's more likely they will each transact with a market maker. Because of the way limit order books work, they cannot possibly receive wors…
> Because of the way limit order books work, they cannot possibly receive worse prices due to the presence of the market maker's orders
The (HFT) profit has to come from somewhere. And I'm pretty sure they come from the other market participants. If that's the case, clearly some market participants are getting a worse deal than they'd otherwise have gotten. At the time scale of seconds, trading is a zero sum game. Perhaps there's something I'm missing?
> is actually called out elsewhere in this comments section as a value-destroying activity that reduces liquidity and therefor at the margin causes less sophisticated traders to get worse prices.
Yes that's how I also understand it. Is this description incorrect?
> If someone is regularly noticing things and adjusting their price in a tenth of a second, it seems likely they are engaged in some form of automated trading.
I'd consider automated trading and HFT to be orthogonal concepts. I totally see the benefit of automating trading, but I don't see the benefit of HFT. The 100ms number was selected small enough to be faster than any "real" "tangible" "physical" process in the economy, but still way slower than HFTs.