The cost of display advertising inventory purchased using programmatic buying technologies is poised to rise by as much as 20% across North America by 2018 due to publishers taking advantage of improved yield optimization technologies, according to a study. The Drum reports "that publishers' continued adoption of header bidding, a generic shift from fixed CPMs to more dynamic pricing models (or dCPMs), as well as improved price-discovery software (including artificial intelligence) will result in a 15-to-20% increase in display ad prices, according to a study by Goodway Group." The study suggests that there will be an average price-increase of 2% each month across all programmatic display purchases before 2018. Goodway Group maintains that smaller agencies' adoption of programmatic technologies is helping drive price increases.