Isn't it simply a question of competition? If some advertisers can't support HTTPS, that means there are fewer bidders for HTTPS content. That should result in

Isn't it simply a question of competition? If some advertisers can't support HTTPS, that means there are fewer bidders for HTTPS content. That should result in a lower price. They are also bidding on what's presumably a shrinking pie of HTTP ad space. If the volume available to buy has dropped considerably, that may also be driving up the price of HTTP ad views.