> A net negative to society, but a positive for the wealthiest.
No.
When your passive index fund manager rebalances every month because “NVDA is now overweighted in VTI, QQQ” the manager does not care about the bid/ask spread.
When VTI is $1.6 trillion, even a $0.01 difference in price translates to a loss $60 million for the passive 401k, IRA, investors.
HFT reduces the bid/ask spread, and “gives this $60 million back” to the passive investors for every $0.01 price difference, every month. Note that VTI mid price at time of writing is $272.49.
