For Bing, powering Yahoo was not good enough.
The Microsoft-owned search engine is now the world's second most popular behind Google and ahead of Yahoo but in the U.S. Bing has not been able to win that same distinction.
The gap between Yahoo and Bing in the U.S. had been drastic up until recently.
ComScore's latest stats reveal that Bing is closing in on Yahoo with a 15 percent market share compared to Yahoo's 15.1 percent.
The study does not take into account mobile search, where Bing's market should be increasing.
Google remained on top with a 65.4 percent share.