Good news for our U.S. advertisers - beginning today, you have an extra ad placement opportunity with the addition of a fourth ad in the mainline above the organic results. (Mainline ads are the ads that appear above algorithmic results, and right-rail ads are those that appear to the right of the algorithmic result set.) With this update we're increasing the ads shown from up to 8 per page to up to 9 per page, which means there is an additional ad placement opportunity for you to vie for in the adCenter auction. In addition, the top two mainline ads will continue to receive essentially a two-for-one ad placement, since they will also display at the bottom of the page in the U.S. Check out the new addition on Live Search.

We've made this change in response to your feedback asking for more clicks for your ads – our test results show that displaying a fourth mainline ad, and also displaying the top two mainline ads again at the bottom of the page, increases clicks to these ads. Over the last several months we've been optimizing our paid search ad layouts to help drive increased revenue for your ads, and provide a positive search experience for users.

We hope you enjoy these updates to help drive more traffic to your sites. We will closely evaluate and monitor the results of this new ad placement layout and will continue to improve or create new ad placement layouts to meet the needs of our searchers and advertisers.