[krisdol]

>By definition successful arbitrage makes the market more efficient - it brings prices closer together (making the cheaper exchange more expensive and the more expensive one cheaper).

Agreed. As header bidding and arbitrage proliferate, we also see ad tech companies targeting the supply side of the equation: with services that help publishers understand how well the header bidding product is performing, which ads work and which dont, and how viewers engage with their site. As pubs are getting more information into the ad selection process, losing exchanges will have to adjust the quality or lower the prices of their ad supply.