comScore has released the top 50 ad networks and top 50 web properties for June 2008.
In ad networks, AOL's Platform-A takes the top spot, reaching 90% of American internet users. Yahoo comes in second, reaching 83% and Google comes in third with 81%. Here's the full list:
In web properties, Google leads the pack 140.2 million unique visitors, but Yahoo comes in a very close second at 140.1 million. This past April, Google's sites beat Yahoo's properties for the first time. Microsoft trails in third with 119 million. AOL is in 4th with 110 million and Fox Interactive rounds out the top 5 with 85 million. Here's the chart: