The implementation shortfall of a sell trade

CFA Level III
#1

How to calculate the Realized Profit/loss of a sell trade?

#2

For a Purchase ->

e.g. you have

Market Impact: (Purchase Execution Price - Previous Day Close price)*# Purchased/(Benchmark Price * Total required)

For Sell Transaction

Market Impact: (Previous Day Close price - Sale Execution Price )*# Sold/(Benchmark Price * Total required)