The key here is that Big Mutual Fund Inc. doesn't want to announce to the world that it's trying to sell a massive volume of shares; it wants to get the deal arranged quietly so that other people in the market don't trade the stock down in anticipation.
The price of the trade will be continually adjusted until the trade is executed. Usually the firm has an approved range to work within. If the price steps outside this range, many more phone calls will ensue.
