The hierarchy of sports betting sites is experiencing some upheaval at the top. That is because more and more data is pointing to a changing of the guard when it comes to the mobile side of legal sports betting market share in the United States. Namely, it looks like DraftKings has seized, or is getting closer to seizing, the top spot from FanDuel, which has long been the leader among U.S. online sports betting operators. DraftKings has typically run second in the rankings, but numbers recently reported by state regulators show DraftKings claiming the top spot, or at least coming within arm’s reach.