Online advertising revenues among the four largest Web advertising companies (Google, Yahoo, Microsoft, and AOL) ramped up 10.2 percent in the fourth quarter to $9 billion.  This marks the second quarter of positive growth following last year’s advertising recession, and growth accelerated from 1.2 percent in the third quarter.

Unlike in the third quarter, Google didn’t account for all the growth. All four companies showed decent sequential increases, indicating that display advertising is beginning to regain its health, and not just search advertising. But search is still driving the gains. Google had another blowout quarter, for instance. And Microsoft showed some strength compared to the previous quarter, perhaps due to Bing search advertising revenues starting to kick in. On a sequential basis, Microsoft’s advertising revenues grew the fastest at 18.6 percent. But the other three weren’t exactly slouching, with growth rates between 11.5 percent and 13.7 percent each

I keep track of these numbers every quarter for these four companies, which turns out to be a good proxy for overall online advertising revenues since they represent a majority of the industry’s revenues. The numbers represent global advertising revenues, and include network revenues paid to affiliates through AdSense and Yahoo’s ad network. Google’s licensing revenues for Google Enterprise Apps have been stripped out. For Microsoft and AOL, I include only the advertising portions of their online revenues as reported in their quarterly earnings statements.

Below is a table with all the numbers:

Online Advertising Revenues (in millions)