Dennis Dick at Trading Defenders has a terrific presentation on the market-destroying fiasco that is known as sub-pennying. If free markets matter, then sub-pennying should be illegal.
The Sub-Pennying Problem
Rockonomics Dot Net
Money – Freedom – Markets
You should post again some day.
It dawned on me that sub-pennying works exactly like taxation. Goldman contributes nothing of value to the trade, not even a facilitating role; they simply skim off a little money because they power to do so.