All four of the major online advertising players have now reported their first-quarter financials and, for the first time, we can see an actual reduction in online ad-spend. Up until now the rate of growth has been slowing, but an actual decline on previous-quarter numbers is new.

Erick Schonfeld has crunched the numbers and shows that in combination, Google, Microsoft, Yahoo and AOL have seen a 7% drop in ad revenue compared to Q4-2008 and even a 2% drop compared to Q1 a year ago. Google is the only network to have managed some small annual growth effectively increasing their dominance during the downturn.