> AFAIK this isn't happening, but why? Is there another moat I don't know of? Well, Adsense / Analytics is another. Google can track you across the internet, a

> AFAIK this isn't happening, but why? Is there another moat I don't know of? Well, Adsense / Analytics is another. Google can track you across the internet, and offer that information to search query bidders. If you don't want to bother spending money advertising to people who read HN, it's achievable. Less so for say, Bing or Yahoo. Being able to target better than other platforms alters your willingness to pay to advertise there vs elsewhere. I suspect they also have a better grasp of the value of traffic acquisition. They pay a lot of web related tech firms to use their search engine over competitor's. We know the only time they lost a bid for Firefox's search placement was when a former Google executive was working for a competitor. It's not clear whether Marissa brought Yahoo some better insight into the value, or if she just needed to accept a higher risk of overpaying for traffic.