• by Joe Mandese  @mp_joemandese, November 26, 2012

In one of the first detailed analyses of the seasonal fluctuations in the supply-and-demand of online display advertising attributable to Thanksgiving and Black Friday, real-time bidding volume crashed as the supply of online ad impressions plummeted due to holiday usage patterns. The result was a spike in the average prices paid by advertisers bidding on inventory during Thanksgiving week.

The analysis released this morning by independent online trading desk Accordant Media suggests that some of the decline in RTB volume during the period was due to pre-holiday inventory sales.

“On one hand, publishers may have achieved higher upfront sell-through (lower RTB inventory) for Black Friday ahead of Cyber Monday, and on the other hand, consumers were probably offline more over the holiday period which also means lower impression volumes,” explains Craig Schinn, vice president-analytics at Accordant.

Whatever the reasons, the facts are that average daily trading volume for RTB impressions fell between 10% and 30% during Thanksgiving week vs. corresponding market averages.

The decline peaked on Thanksgiving day, which saw average RTB impressions volume fall 30% over an average Thursday’s trading volume.

While that might not seem surprising given the seasonal repast, Accordant notes that Black Friday auction volume was also down 20% over a typical Friday.

“The decreased inventory levels made for a much more frenetic ad-buying environment,” the Accordant report notes, adding: “With auction CPMs as much as 50% higher, buyers face greater pressure to make certain they are finding the quality audience they are looking for or face overall campaign performance challenges.”