[secretasiandan]

Can you tell me more about these commitments and what makes them expensive?

No one may explicitly choose to trade with HFT firms, but that doesn't mean they don't value their presence

"Although Vanguard does not engage in "high frequency trading" and does not operate a "dark pool," we believe much of the public concern over "high frequency trading" is misplaced and believes such activity, appropriately examined, contributes to a more efficient market that benefits all investors."

http://www.sec.gov/comments/s7-02-10/s70210-122.pdf

[yummyfajitas]

He is probably referring to NASDAQ market makers, who are obligated to have a quote at the NBBO at least 10-15% of the time. Of course, there is no obligation that their 10-15% include the 1 hour or so of the flash crash...

[secretasiandan]

I really just wanted him to describe why he thought that obligation was "expensive"