Suppose I have portfolio of three stocks and lets say my routine wants to sell one of them (stock A), buy one of them (stock B) and make no changes to the last one (stock C). Assume I know the share of stocks A & B that I want to set (say -50% and 50% of what is remaining after Share C) and stock C unchanged. How to do this?
I think one needs to remember current share of stock C. Is it possible?