webcentric - 3:55 am on Sep 6, 2013 (gmt 0)
Down from $240/day for 3 days to $70/day past 3 days.
If you're using enhanced text ads, you might want to take a look a your sites to see if these changes are in effect anywhere. They could be related to the decrease. They just appeared on my site today and seemed to have an almost immediate dampening effect on CTR. I'm not saying the changes are bad, only that they ad a certain graphical flare to the page that may or may not be desirable, depending on your layout. The new formats also move the ad's hot spot in certain circumstances.