If HFT lets Vanguard lower their costs, the savings of which are passed on to their customers, that's more money in the retirement accounts of regular people.

If HFT lets Vanguard lower their costs, the savings of which are passed on to their customers, that's more money in the retirement accounts of regular people. I just got an email that the expense ratio of my Vanguard target date fund is going down, so costs were reduced somewhere.