* We recalculate/update size of the pair order every time parent fills (even on partial trade) based on the size of the parent order traded up to that moment, so we do not accumulate rounding errors
* in other words: size_of_hedge = roundDown(ratio* total_parent_fill)
Thanks for the great responses dst ... the hedge calculation is the most important issue so can you please provide more clarification (truthfully I am confused):
1.
True or False: hedge quantity for a full parent execution (no partial fills) = round_down(ratio * parent_quantity) = Truncate_to_integer(ratio * parent quantity)?
2.
True or False: Denote by N the full hedge quantity from (1). Then no matter how many partial fills there are, the algorithm ensures that if the full parent order eventually gets executed, the total quantity of all transmitted hedge orders is exactly N?
3.
This is where I'm definitely confused, so an example would really help: Suppose the parent order executes completely in 3 partial fills of parent order quantities M1, M2, M3 ... then what are the formulas for N1, N2, N3, the hedge order quantities transmitted upon each partial fill?
4.
Suppose I'm hedging 100 shares stock XYZ with 100 shares stock ABC (ratio = 1.0) and the parent order executes in 100 partial fills of 1 share each (this is a real example; dozens of tiny partial fills are common with HFT activity). Then do I pay 100 commissions on the hedges, or 1 commission, or something else?
P.S. I've got screen shots to send you but I did not get your PM.