Is anyone aware if the market makers are under any type of best execution constraints other than not violating NBBO? For example, say the NBBO is 101.10 / 101.90 in stock XYZ. Customer1 send a limit order to buy at 101.50. The broker forwards the order to a MM. Customer2 then sends a market order to sell in XYZ. The broker then sends that order to the same MM. Does the MM have any obligation cross the order at 101.50 (or offer price improvement over the 101.50 bid)? Or can they fill both and pocket the free $.40?
Also, I don't think any firms will publish this, but does anyone have any insight on how the broker decides which MM receives a given order?
Also, I don't think any firms will publish this, but does anyone have any insight on how the broker decides which MM receives a given order?