Wienke is correct. The volume-weighted average price (VWAP) is a weighted average of security prices during a day, where the weight applied is the proportion of the day's trading volume. It is useful because it can be applied quickly and easily.
Brooks is incorrect. Although it is true that a trader may try to game the volume-weighted average price by delaying the trade, the trader would wait until the ask price is less than the volume-weighted average price. Although it would appear that the trader has minimized trading costs in this case, the level of overall prices could have increased so that the trade should have been executed earlier
