The FUCK!
Qlai, buy my apple for $1.000. You buy my apple for $1.000. I buy back the apple I sold you for the same price you bought it from me. $1.000
So who made money?
Where is the money being made? Something stinks about that crap, man. HFT must die. Re-open the pits, and make it an Octagon. lol!
The two apples are on different exchanges and your access is slower both for quotes and execution.
It’s easier to see as price differential, how there is an arb opportunity.
Via decimalization, in addition to having faster infrastructure both for quotes and execution they cut to the head of the line on both exchanges.
When price looks the same, via depth it is not.
10k of $1000 apples is not the same as 11k of $1000 apples. The difference in qty needed to complete the trade requires for the corresponding imbalance to be filled by crossing of the spread. Since they have an informational and infrastructure advantage, they’ve already positioned themselves to be the first order in line to receive the spread.
When both price and depth look the same, then the pace of resupply at limit is where the imbalance would be exploited.
Those are simplistic versions of it being done in equities with the footprints on T&S as share prices with subpennies.
To mitigate the tax on trading extracted by hft’s as lone retailer without the same hardware/software/infrastructure/specialized knowledge investment, one would have to trade fractals on higher timeframes.