On Monday, the shares of GME close at $20.00 per share. - On Tuesday, before trading begins, a portfolio manager decides to buy GME. An order goes to the trading desk to buy 1,000 shares of GME at $19.50 per share or better, good for one day. The benchmark price is Monday's close at $20.00 per share. No part of the limit order is filled on Tuesday, and the order expires. The closing price on Tuesday rises to $22.50. - On Wednesday, the trading desk again tries to buy GME by entering a new limit order to buy 1,000 shares at $23.50 per share or better, good for one day. During the day, 600 shares are bought at $23.50 per share. Commissions and fees for this trade are $25. Shares for GME close at $24.05 per share on Wednesday. No further attempt to buy GME is made, and the remaining 400 shares of the 1,000 shares the portfolio manager initially specified are canceled. - How much is the implementation shortfall in this case