…and do others see this jump at midnight in their own timezone?
This question was asked on Quora.com, below is my answer.

I dug into this win price problem several months ago after noticing the same jump in spend at that hour. Rubicon is on Pacific time so we refer to this as the “9 O’Clock Bump” effect.

Dr. Richter pointing at a Dodo bird. “Adapt or perish”

After asking several DSPs about the problem we determined that it was, indeed, campaign budgets resetting combined with less-than-optimal pacing algorithms and in some cases lack thereof.

We’re in the process of finishing up some documentation on our pacing algorithm that does a pretty good job pacing to the needs of the campaign while considering the fairly predictable traffic pattern throughout the day. We’ll be putting this information out in the next couple weeks. Hopefully it will inspire some folks in the market to upgrade their systems and resolve some of this win price inefficiency. I’ll update post with a link to the document once we release it.

UPDATE: The document is finally out the door. You can read it here.