After some thought, this sort of seems like it's missing the point. What I'm curious about is what the current state of cookie and user click stream sharing am

After some thought, this sort of seems like it's missing the point. What I'm curious about is what the current state of cookie and user click stream sharing among analytics/advertising companies is. What proportion of my browsing history is known to any given company, and what proportion given collusion? Are there any studies on this?