According to the Tabb Group's May 2014 report Truing the Block, "...larger investors believe that 20% of ADV is a reasonable amount of volume that can be safely and effectively bought without incurring negative market impact on price."

In JonesTrading's view, this means that larger investors have two options to avoid trading larger orders without negatively impacting price: trading the order in a block or spreading the order out over additional days by trading 20% of the average daily volume ("ADV") each day.

By trading a block the investor can quantify the "days saved". Furthermore they can eliminate the uncertainties that the unknown future will bear on a real time investment thesis.